Binomial Series (Edexcel IGCSE Further Pure Maths): Exam Questions

Exam code: 4PM1

41 mins5 questions
1a
3 marks

Expand open parentheses 1 space plus space 2 x squared close parentheses to the power of negative 3 over 4 end exponent in ascending powers of x up to and including the term in x to the power of 6

Express each coefficient as an exact fraction in its lowest terms.

straight f open parentheses x close parentheses space equals space fraction numerator open parentheses 2 space plus space k x close parentheses over denominator open parentheses 1 plus 2 x squared close parentheses to the power of 3 over 4 end exponent end fraction where k space not equal to 0

1b
2 marks

Obtain a series expansion for straight f left parenthesis x right parenthesis in ascending powers of x up to and including the term in x to the power of 5

Give each coefficient in terms of k where appropriate.

1c
2 marks

The coefficient of the term in x to the power of 5 is fourteen times the coefficient of the term in x squared

Find the value of k

2a
2 marks

Show that

fraction numerator a over denominator square root of 4 plus b x end root end fraction equals a over 2 open parentheses 1 plus fraction numerator b x over denominator 4 end fraction close parentheses to the power of negative 1 half end exponent where a and bare positive integers.

The expansion of fraction numerator a over denominator square root of 4 plus b x end root end fraction in ascending powers of xcan be written as

P plus Q x plus R x squared plus S x cubed

where P, Q, R and S are rational numbers.

2b
4 marks

Show that Q equals negative fraction numerator a b over denominator 16 end fraction and S equals negative fraction numerator 5 a b cubed over denominator 2048 end fraction

and find P and R in terms of a and b, as fractions in their lowest terms.

2c
3 marks

Given that Q equals 128 over 5 S and R equals 9 over 256

show that a = 3 and b =1

2d
3 marks

Hence, using an appropriate value of x, find, to 3 decimal places, an approximate value for fraction numerator square root of 6 over denominator 2 end fraction

3a
3 marks

Expand open parentheses 1 plus x over 3 close parentheses to the power of negative 3 end exponent in ascending powers of x up to and including the term in x cubed

Where appropriate express each coefficient as an exact fraction in its lowest terms.

3b
1 mark

Write down the range of values of x for which your expression is valid.

3c
2 marks

Express open parentheses 3 plus x close parentheses to the power of negative 3 end exponent in the form P space open parentheses 1 plus Q x close parentheses to the power of negative 3 end exponent where P and Q are rational numbers whose values should be stated.

3d
2 marks

straight f left parenthesis x right parenthesis equals fraction numerator 1 plus 4 x over denominator left parenthesis 3 plus x right parenthesis cubed end fraction

Obtain a series expansion for straight f open parentheses x close parentheses in ascending powers of x up to and including the term in x squared

4a
3 marks

Expand left parenthesis 1 minus 8 x squared right parenthesis to the power of negative 1 half end exponent in ascending powers of x, up to and including the term in x to the power of 6 giving each coefficient as an integer.

4b
4 marks

straight g left parenthesis x right parenthesis equals fraction numerator a plus b x over denominator square root of 1 minus 8 x squared end root end fraction where a and b are prime numbers

Given that the fourth and fifth terms, in ascending powers of x, in the series expansion of straight g open parentheses x close parentheses are 20x cubedand 48x to the power of 4 respectively,

find the value of a and the value of b

5a
2 marks

Given that open parentheses 8 plus 3 x close parentheses to the power of 1 third end exponent can be expressed in the form p open parentheses 1 plus q x close parentheses to the power of 1 third end exponent where p and q are constants,

find the value of p and the value of q

5b
3 marks

Hence, expand open parentheses 8 plus 3 x close parentheses to the power of 1 third end exponent in ascending powers of x up to and including the term in x2 , expressing each coefficient as an exact fraction in its lowest terms.

5c
2 marks

Using the expansion found in part (b) with a suitable value of x

show that cube root of 9 almost equal to 599 over 288