General Binomial Expansion (OCR A Level Maths A: Pure): Exam Questions

Exam code: H240

4 hours39 questions
1a
2 marks

Find the first three terms, in ascending powers of x, of the binomial expansion of

        left parenthesis 1 plus x right parenthesis to the power of negative 2 end exponent

giving each term in simplest form.

1b
1 mark

State the range of values of x for which the expansion in part (a) is valid.

2
3 marks

Find, in ascending powers of x, the binomial expansion of

         open parentheses 1 minus x close parentheses to the power of negative 1 end exponent

up to and including the term in x squared.

3
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3 marks

Find, in ascending powers of x, the binomial expansion of

        left parenthesis 1 plus 2 x right parenthesis to the power of negative 1 half end exponent

up to and including the term in x cubed.

4a
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3 marks

Find the first three terms, in ascending powers of x, of the binomial expansion of

      space open parentheses 1 minus 1 half x close parentheses to the power of 1 third end exponent

giving each term in simplest form.

4b
1 mark

State the range of values of x for which the expansion in part (a) is valid.

5
2 marks

Find the coefficient of the term in x squared in the binomial expansion of

        left parenthesis 1 minus 3 x right parenthesis to the power of negative 3 end exponent

6a
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2 marks

Given that x is small, so that x cubed and higher powers of x can be ignored, show that

            open parentheses 1 minus 1 third x close parentheses to the power of negative 2 end exponent almost equal to 1 plus 2 over 3 x plus 1 third x squared

6b
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1 mark

By substituting x equals 0.18 into the result from part (a), find an estimate for the value of left parenthesis 0.94 right parenthesis to the power of negative 2 end exponent.

7a
1 mark

Show that

         square root of 4 minus 4 x end root identical to 2 left parenthesis 1 minus x right parenthesis to the power of 1 half end exponent

7b
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3 marks

Hence find, in ascending powers of x, the first three terms of the binomial expansion of

      square root of 4 minus 4 x end root

giving each term in simplest form.

7c
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1 mark

Use x equals 0.02 and your expansion from part (b) to find an approximation to  2 square root of 0.98 end root.

1a
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3 marks

Find the first three terms, in ascending powers of x, of the binomial expansion of

               square root of 1 plus 2 x end root 

giving each term in simplest form.

1b
1 mark

State the range of values of x for which the expansion in part (a) is valid.

1c
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2 marks

By choosing a suitable value of x, use your expansion from part (a) to estimate square root of 1.06 end root

Give your estimate to 3 significant figures.

2
3 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 1 minus x close parentheses squared

up to and including the term in x cubed.

Give each term in simplest form.

3
2 marks

The function straight f left parenthesis x right parenthesis is given by

           straight f left parenthesis x right parenthesis equals left parenthesis 1 minus p x right parenthesis to the power of negative 4 end exponent

where p is an integer.

Find, in terms of p, the coefficient of the term in x cubed in the binomial expansion of straight f left parenthesis x right parenthesis.

4
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4 marks

Find, in ascending powers of x, the binomial expansion of

1 over open parentheses 4 plus 8 x close parentheses squared

up to and including the term in x cubed.

Give each term in simplest form.

5a
3 marks

Given that

         fraction numerator 5 minus x over denominator open parentheses 1 plus x close parentheses open parentheses 1 minus x close parentheses end fraction identical to fraction numerator A over denominator 1 plus x end fraction plus fraction numerator B over denominator 1 minus x end fraction

find the values of A and B.

5b
4 marks

Find the first three terms, in ascending powers of x, of the binomial expansions of

(i)  3 left parenthesis 1 plus x right parenthesis to the power of negative 1 end exponent

(ii) 2 left parenthesis 1 minus x right parenthesis to the power of negative 1 end exponent

5c
1 mark

Hence show that the first three terms, in ascending powers of x, in the binomial expansion of

            fraction numerator 5 minus x over denominator open parentheses 1 plus x close parentheses open parentheses 1 minus x close parentheses end fraction

are

               5 minus x plus 5 x squared

5d
1 mark

Find the range of values of x for which the expansion of fraction numerator 5 minus x over denominator open parentheses 1 plus x close parentheses open parentheses 1 minus x close parentheses end fraction converges.

6a
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3 marks

Use the binomial expansion to show that the first three terms in the expansion of  left parenthesis 1 plus 2 x right parenthesis to the power of negative 3 end exponent are  

1 minus 6 x plus k x squared

where k is a constant to be found.

6b
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3 marks

Hence find the first three terms, in ascending powers of x, of the binomial expansion of

fraction numerator 1 plus x over denominator open parentheses 1 plus 2 x close parentheses cubed end fraction

giving each term in simplest form.

State also the range of values of x for which the expansion is valid.

7a
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4 marks

The function straight f left parenthesis x right parenthesis is given by

straight f left parenthesis x right parenthesis equals open parentheses 1 minus 1 half x close parentheses to the power of 1 half end exponent

(i) Expand straight f left parenthesis x right parenthesis in ascending powers of x up to and including the term in x squared.

(ii) Find the range of values of x for which this expansion is valid.

7b
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4 marks

The function straight g left parenthesis x right parenthesis is given by

straight g left parenthesis x right parenthesis equals left parenthesis 2 plus x right parenthesis to the power of negative 2 end exponent

(i) Expand straight g left parenthesis x right parenthesis in ascending powers of x up to and including the term in x squared.

(ii) Find the range of values of x for which this expansion is valid.

7c
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4 marks

(i) Find the expansion of fraction numerator square root of 1 minus 1 half x end root over denominator open parentheses 2 plus x close parentheses squared end fraction in ascending powers of x, up to and including the term in x squared.

(ii) Find the range of values of x for which this expansion is valid.

8a
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4 marks

The function straight f left parenthesis x right parenthesis is given by

            straight f left parenthesis x right parenthesis equals square root of 4 minus s x end root

where s is a non-zero integer.

In the binomial expansion of straight f left parenthesis x right parenthesis, find in terms of s

(i) the coefficient of the term in x

(ii) Find the coefficient of the term in x squared

8b
1 mark

In the binomial expansion of straight f left parenthesis x right parenthesis, the coefficient of the term in x is equal to the coefficient of the term in x squared.

Find the value of s.

9
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3 marks

Two functions are given by

straight f open parentheses x close parentheses equals square root of 1 plus a x end root

straight g open parentheses x close parentheses equals cube root of 1 minus a x end root

where a is a non-zero constant.

In their binomial expansions, the coefficient of the term in x squared from straight f left parenthesis x right parenthesis is equal to the coefficient of the term in x from straight g left parenthesis x right parenthesis.

Find the value of a.

10a
3 marks

Express fraction numerator 2 over denominator open parentheses 1 minus x close parentheses open parentheses 1 plus x close parentheses end fraction in partial fractions.

10b
4 marks

Find the first three terms, in ascending powers of x, of the binomial expansions of

(i)  open parentheses 1 minus x close parentheses to the power of negative 1 end exponent

(ii) open parentheses 1 plus x close parentheses to the power of negative 1 end exponent

10c
1 mark

Hence show that 

fraction numerator 2 over denominator open parentheses 1 minus x close parentheses open parentheses 1 plus x close parentheses end fraction equals alpha plus beta x squared plus...

where alpha and beta are constants to be found.

10d
1 mark

Find the range of values of x for which the expansion in part (c) is valid.

11
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3 marks

Find, in ascending powers of x, the binomial expansion of

            1 over open parentheses 1 minus 2 x close parentheses cubed

up to and including the term in x cubed.

Give each term in simplest form.

12
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4 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 4 plus x close parentheses cubed

up to and including the term in x cubed.

Give each term in simplest form.

13a
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3 marks

Use the binomial expansion to expand open parentheses 1 minus begin inline style 1 half end style x close parentheses to the power of begin inline style 1 third end style end exponent  up to and including the term in x squared.

Give each term in simplest form.

13b
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2 marks

Hence expand  open parentheses 1 minus x close parentheses open parentheses 1 minus 1 half x close parentheses to the power of 1 third end exponent up to and including the term in x squared.

14
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3 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 1 minus 1 third x close parentheses to the power of 4

up to and including the term in x cubed.

Give each term in simplest form.

1a
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5 marks

Use the first three terms, in ascending powers of x of the binomial expansion of

              open parentheses 1 plus 4 x close parentheses to the power of begin inline style 1 third end style end exponent

to estimate the value of cube root of 1.2 end root, giving your estimate to 3 significant figures.

1b
1 mark

Explain why your estimate in part (a) is valid.

2
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4 marks

In the binomial expansion of  open parentheses 1 minus begin inline style 1 fourth end style x close parentheses to the power of n where n is a negative integer, the coefficient of the term in x squared is begin inline style 3 over 8 end style.

Find the value of n.

3a
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7 marks

A function is given by

straight f open parentheses x close parentheses equals open parentheses 1 minus 1 third x close parentheses to the power of negative 1 end exponent open parentheses 2 minus x close parentheses to the power of negative 2 end exponent

Given that x is small, such that terms in x cubed and higher powers of x can be ignored, show that

        straight f open parentheses x close parentheses almost equal to 1 fourth plus 1 third x plus k x squared

where k is an exact constant to be found.

3b
1 mark

Find the range of values of x for which the expansion in part (a) is valid.

3c
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3 marks

Find, to 3 significant figures, the percentage error when using the approximation in part (a) to estimate straight f open parentheses 1 half close parentheses.

Show clear working.

4
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6 marks

Two functions are given by

straight f open parentheses x close parentheses equals square root of 9 plus p x end root

straight g open parentheses x close parentheses equals fourth root of 16 plus p x end root

where p is a non-zero constant.

In their binomial expansions, the coefficient of the term in x squared from straight f left parenthesis x right parenthesis is equal to the coefficient of the term in x from straight g left parenthesis x right parenthesis.

Find the value of p.

5
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5 marks

In the binomial expansion of 1 over open parentheses 3 plus p x close parentheses cubedwhere p not equal to 0, the coefficient of the term in x squared is double the coefficient of the term in x cubed

Find the value of  p.

6a
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4 marks

The functions straight f left parenthesis x right parenthesis and  straight g left parenthesis x right parenthesis are given by

straight f left parenthesis x right parenthesis equals open parentheses 4 plus 3 x close parentheses to the power of 1 half end exponent

straight g left parenthesis x right parenthesis equals open parentheses 9 minus 2 x close parentheses to the power of negative 1 half end exponent

Find the first three terms, in ascending powers of x, of the binomial expansion of straight f left parenthesis x right parenthesis.

6b
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4 marks

Find the first three terms, in ascending powers of x, of the binomial expansion of straight g left parenthesis x right parenthesis.

6c
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2 marks

Find the first three terms, in ascending powers of x, of the expansion of

square root of fraction numerator 4 plus 3 x over denominator 9 minus 2 x end fraction end root 

giving each term in simplest form.

6d
1 mark

Find the range of values of x for which your expansion in part (c) is valid.

7
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4 marks

In the expansion of  begin mathsize 20px style open parentheses 1 minus begin inline style 4 over 3 end style x close parentheses to the power of n end style where n is a rational number, the coefficient of the term in x squared is begin mathsize 20px style begin inline style negative 16 over 81 end style end style.

Find the possible values of n.

8a
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8 marks

Given that x is small, so that terms in x cubed and higher powers of x can be ignored, show that

         stretchy left parenthesis 2 plus 3 x stretchy right parenthesis to the power of negative 1 end exponent stretchy left parenthesis 3 minus 2 x stretchy right parenthesis to the power of negative 2 end exponent almost equal to 1 over 18 minus 1 over 108 x plus 19 over 216 x squared

8b
1 mark

Find the range of values of x for which the approximation in part (a) is valid.

8c
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3 marks

Find, to 1 decimal place, the percentage error when using the approximation in part (a) to estimate the value of fraction numerator 1 over denominator stretchy left parenthesis 2 plus 3 x stretchy right parenthesis stretchy left parenthesis 3 minus 2 x stretchy right parenthesis squared end fraction at x equals 0.1

9a
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3 marks

Express fraction numerator 12 minus x over denominator open parentheses x plus 2 close parentheses open parentheses 3 minus x close parentheses end fraction  in partial fractions.

9b
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7 marks

Hence use binomial expansions to show that

fraction numerator 12 minus x over denominator open parentheses x plus 2 close parentheses open parentheses 3 minus x close parentheses end fraction equals 2 minus 1 half x plus m x squared plus...

where m is a constant to be found.

9c
1 mark

Find the range of validity of x for the expansion in part (b).

10a
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5 marks

In the binomial expansion of  square root of 4 plus begin inline style p over q end style x end root   where p less than 0 less than q, the coefficient of the term in x squared is equal to the coefficient of the term in x cubed.

Show that p equals negative 8 q.

10b
3 marks

Given that the product of p and q is negative 8, find the values of p and q.

1a
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5 marks

Use the first three terms, in ascending powers of x, in the binomial expansion of

         fraction numerator 1 over denominator square root of 1 minus 1 half x end root end fraction

to estimate the value of fraction numerator 1 over denominator square root of 0.95 end root end fraction, giving your estimate to 2 decimal places.

1b
2 marks

Explain why you would not be able to use the expansion in part (a) to estimate fraction numerator 1 over denominator square root of 3 end fraction.

2
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5 marks

Find the first three terms in ascending powers of xof the binomial expansion of

fraction numerator 1 minus x over 2 over denominator square root of 9 plus 3 x end root end fraction

giving each term in simplest form.

3
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5 marks

In the binomial expansion of   fraction numerator 1 over denominator cube root of 8 plus 2 q x end root end fraction where q not equal to 0,  the coefficient of the term in x squared is one-seventh of the coefficient of the term in x cubed

Find the value of q.

4
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7 marks

Expand

cube root of fraction numerator 8 minus x over denominator 8 plus 2 x end fraction end root

in ascending powers of x, up to and including the term in x squared

Find also the range of values of x for which this expansion is valid.

5
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8 marks

Two functions are given by

 straight f left parenthesis x right parenthesis equals square root of 4 plus a x end root 

straight g left parenthesis x right parenthesis equals fourth root of 16 plus b x end root

where a and b are non-zero constants.

The binomial expansions of  straight f left parenthesis x right parenthesis  and  straight g left parenthesis x right parenthesis have the following properties:

  • The coefficient of the x cubed term in the expansion of straight f open parentheses x close parentheses is 72 times larger than the coefficient of the x squared term in the expansion of straight g open parentheses x close parentheses

  • The coefficient of the x term in the expansion of straight f open parentheses x close parentheses is 24 times larger than the coefficient of the x term in the expansion of straight g open parentheses x close parentheses

Find the values of a and b.

6a
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8 marks

Use binomial expansions to show that, in ascending powers of x

15 open parentheses x minus 4 close parentheses to the power of negative 1 end exponent open parentheses 5 x minus 2 close parentheses to the power of negative 1 end exponent equals a plus b x plus c x squared plus...

where a, b and c are constants to be found.

6b
2 marks

Explain why the expansion found in part (a) cannot be used to estimate the value of

fraction numerator 15 over denominator open parentheses 0.6 minus 4 close parentheses open parentheses 5 cross times 0.6 minus 2 close parentheses end fraction

7a
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10 marks

Use binomial expansions to show that, in ascending powers of x,

fraction numerator 2 open parentheses 2 minus 5 x plus x squared close parentheses over denominator open parentheses x plus 2 close parentheses open parentheses 2 minus x close parentheses squared end fraction equals alpha plus beta x plus gamma x squared plus...

where alpha, beta and gamma are constants to be found.

7b
1 mark

Find the range of values of x for which the expansion is valid.

8
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7 marks

In the expansion of open parentheses 16 minus 2 x close parentheses to the power of n where n is a rational number, the coefficient of the term in x squared is

5 cross times 2 to the power of 4 n minus 11 end exponent

Given that vertical line n vertical line less than 1, find the value of n.