Find
(i) Solve
(ii) Hence find the range of values of for which
is concave.
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Exam code: 9MA0
Find
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(i) Solve
(ii) Hence find the range of values of for which
is concave.
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The curve has equation
Find
(i)
(ii)
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(i) Verify that has a stationary point at
(ii) Show that this stationary point is a point of inflection, giving reasons for your answer.
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The curve has equation
Find expressions for and
.
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(i) Write down the value of for which
.
(ii) By considering the sign of either side of this value of
, prove that
has a point of inflection.
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Hence find the coordinates of the point of inflection on .
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The curve has equation
Show that
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Hence find the set of values of for which
is concave.
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In a computer animation, the side length, mm, of a square is increasing at a constant rate of
.
Let be the area of the square.
Find in terms of
.
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Find the rate at which the area of the square is increasing when .
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The curve has equation
Find the value of and the value of
at the point on
where
.
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Show that has a point of inflection at
.
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Explain why this point of inflection is not a stationary point.
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The continuous curve has equation
, where
.
Given that
crosses the
-axis at
and the
-axis at
is concave for
is convex for
,
and
are constants such that
sketch the curve .
On your sketch, label the coordinates of the points where crosses the coordinate axes and the coordinates of the point of inflection.
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The side length, , of a cube is increasing at a constant rate of
.
Let be the volume of the cube.
Find in terms of
.
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Find the rate at which the volume of the cube is increasing when .
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In a simple model, the rate of increase of the radius, , of a sphere with respect to time,
seconds, is directly proportional to the temperature,
, of its immediate surroundings.
Write down a differential equation for this model, using as the constant of proportionality.
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Given that when the surrounding temperature is , the radius of the sphere is increasing at a rate of
, find the value of
.
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A cube has side length , surface area
and volume
.
Show that
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The volume of the cube is decreasing at a constant rate of .
Find the rate at which the surface area of the cube is decreasing when .
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A tank in the shape of a cuboid is being filled with water.
The base of the tank measures 20 m by 10 m and the height of the tank is 5 m, as shown in Figure 1.
At time minutes after water started flowing into the tank the height of the water was
m and the volume of the water in the tank was
m3.
In a model of this situation
the sides of the tank have negligible thickness
the rate of change of is inversely proportional to the square root of
Show that
where is a constant.
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A large spherical balloon is deflating.
At time seconds the balloon has radius
cm and volume
cm3.
The volume of the balloon is modelled as decreasing at a constant rate.
Using this model, show that
where is a positive constant.
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The curve has equation
Find the coordinates of the point of inflection on .
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The curve has equation
Show that
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Solve the inequality
and hence determine the set of values of for which
is convex.
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In a computer animation, the radius, , of a circle is increasing at a constant rate of
.
Find the rate at which the area of the circle is increasing at the instant when the radius is .
Give your answer as a multiple of .
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The curve has equation
Find the coordinates of the stationary points on
.
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Determine the nature of the stationary points found in part (a).
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Determine the coordinate of the point of inflection on
.
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Explain why, in this case, the point of inflection is not a stationary point.
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The continuous curve has equation
, where
.
The graph of has the following properties:
crosses the
-axis at the points
,
and
, where
crosses the
-axis at
The turning points of have
coordinates
and
, where
is concave for
is convex for
Given also that , sketch the curve
.
On your sketch, label the coordinates of the points where crosses the coordinate axes, and mark the
coordinates of the turning points and the point of inflection.
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The side length, , of a cube is increasing at a constant rate of
.
Assuming that the cube remains cubical at all times, find the rate of change of the volume of the cube at the instant when .
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In the production process of a glass sphere, hot glass is blown such that the radius, , increases over time,
seconds.
The rate of increase of the radius is directly proportional to the temperature, , of the glass.
Let be the volume of the glass sphere.
Find an expression, in terms of ,
and a constant of proportionality
, for the rate of change of the volume of the sphere.
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When the temperature of the glass is , the sphere has a radius of
and its volume is increasing at a rate of
.
Find the rate of increase of the radius at this instant.
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An ice cube, of side length , is melting such that its volume is decreasing at a constant rate of
.
Assuming that the ice cube remains in the shape of a cube whilst it melts, find the rate at which its surface area is decreasing at the instant when .
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A bowl is in the shape of a hemisphere of radius .
The volume of liquid in the bowl, , is given by the formula
where is the depth of the liquid.
Liquid is leaking through a small hole in the bottom of the bowl at a constant rate of .
Find the rate of change of the depth of the liquid in the bowl at the instant when .
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Water flows at a constant rate into a large tank.
The tank is a cuboid, with all sides of negligible thickness.
The base of the tank measures 8 m by 3 m and the height of the tank is 5 m.
There is a tap at a point at the bottom of the tank, as shown in Figure 5.
At time minutes after the tap has been opened
the depth of the water in the tank is metres
water is flowing into the tank at a constant rate of m3 per minute
water is modelled as leaving the tank through the tap at a rate of m3 per minute
Show that, according to the model,
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The curve has equation
Determine the number of points of inflection on and determine their coordinates.
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The function is defined by
Find the set of values of for which the curve
is concave.
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The surface area, , of a spherical air bubble is increasing at a constant rate of
.
Given that the surface area of a sphere is , where
is the radius of the bubble,
find an expression, in terms of , for the rate at which the radius of the bubble is increasing.
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The curve has equation
Find the coordinates of the stationary points on , and determine their nature.
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Determine the coordinates of any points of inflection on , and hence state the intervals in which
is convex and concave.
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The diagram below shows a sketch of the graph with equation
Figure 1 shows a sketch of a continuous curve with equation .

On the sketch in Figure 1,
(i) mark the approximate locations of the intercepts with the coordinate axes using the letter
(ii) mark the approximate locations of the stationary points using the letter
(iii) mark the approximate locations of the points of inflection using the letter
(iv) highlight the sections of the curve where the graph is convex.
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A container is in the shape of an inverted right circular cone. The radius of the base of the cone is and the height of the cone is
.
Sand is poured into the container at a constant rate of .
Find the rate of change of the depth of the sand in the cone at the instant when the radius of the sand is .
[The volume, , of a cone with radius
and height
is given by
.]
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A spherical balloon is being inflated.
At time seconds, where
, the radius,
, of the balloon is modelled by the equation
The material used to make the balloon is designed such that the balloon will burst if the rate of increase of its volume exceeds .
Show that the maximum time for which the balloon can be inflated without bursting is seconds.
[The volume, , of a sphere with radius
is given by
.]
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An ice lolly is in the shape of a cylinder.
At time seconds, the cylinder has radius
and length
.
The ice lolly is melting such that its volume is decreasing at a constant rate of .
Assuming that the ice lolly remains mathematically similar to its original shape whilst it melts, find the rate at which its surface area is decreasing at the instant when .
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The volume of liquid, , in a hemispherical bowl is given by the formula
where is the radius of the bowl and
is the depth of the liquid.
Liquid is leaking through a small hole in the bottom of the bowl at a rate directly proportional to the depth of the liquid.
Show that the depth of the liquid in the bowl is decreasing by
where is a constant.
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The curve has equation
Show that there are two points of inflection on .
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Find the coordinates of these two points of inflection, giving your answers to 3 significant figures.
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The curve has equation
Show that is convex in the interval
.
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A plant pot is in the shape of an inverted square-based pyramid. The plant pot has a height of (
) and a base side length of
.
Soil is added to the plant pot at a constant rate of .
Find the rate at which the depth of the soil is increasing at the instant when the depth is .
[The volume, , of a pyramid with base area
and height
is given by
.]
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The curve has equation
Find the coordinates of the stationary points on , and determine their nature.
Give all numerical values in your answer to 3 significant figures.
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Find the coordinates of any points of inflection on , and determine whether they coincide with the stationary points.
Hence state the intervals in which is convex and concave.
Give all numerical values in your answer to 3 significant figures.
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The curve has equation
and the curve
has equation
.
Explain why has a point of inflection which is also a stationary point, but
has a point of inflection that is not a stationary point.
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On the same diagram, sketch the curves and
.
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An expanding spherical air bubble has radius at time
seconds, where
.
The radius of the bubble is modelled by the equation
The bubble will burst if the rate of increase of its volume exceeds .
Find the length of time the bubble expands for, giving your answer to 1 decimal place.
[The volume, , of a sphere with radius
is given by
.]
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A container is in the shape of a right circular cone. The container rests on its flat, horizontal circular base, with its vertex pointing vertically upwards. The height of the cone is and the radius of its base is
.
Salt is poured into the container through a small hole at its vertex at a constant rate of .
Find the rate of change of the depth of the salt at the instant when the container is half full by volume, giving your answer to 3 significant figures.
[The volume, , of a cone with radius
and height
is given by
.]
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A large block of ice, used by sculptors, is in the shape of a cuboid.
At time seconds, the dimensions of the cuboid are
by
by
.
The block melts uniformly such that its surface area is decreasing at a constant rate of , where
is a positive constant.
You may assume that as the block melts, it remains mathematically similar to its original shape.
Show that the rate of decrease of the volume of the block is given by
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In the case when , the block of ice remains solid enough to be sculpted as long as the rate of decrease of its volume does not exceed
.
Find the value of for the largest block of ice that can be used for ice sculpting under these conditions, giving your answer as a fraction in its lowest terms.
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The volume of liquid, , in a hemispherical bowl is given by the formula
where is the radius of the bowl and
is the depth of the liquid.
Liquid is leaking through a small hole in the bottom of the bowl at a rate directly proportional to the depth of the liquid.
When the bowl is full, the rate of volume loss is .
Show that the rate of change of the depth of the liquid is inversely proportional to
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