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Date May 2022 Marks available 1 Reference code 22M.1.AHL.TZ1.7
Level Additional Higher Level Paper Paper 1 Time zone Time zone 1
Command term Find Question number 7 Adapted from N/A

Question

A slope field for the differential equation dydx=x2+y2 is shown.

Some of the solutions to the differential equation have a local maximum point and a local minimum point.

Write down the equation of the curve on which all these maximum and minimum points lie.

[1]
a.i.

Sketch this curve on the slope field.

[1]
a.ii.

The solution to the differential equation that passes through the point (0, 2) has both a local maximum point and a local minimum point.

On the slope field, sketch the solution to the differential equation that passes through (0, 2).

[2]
b.

Markscheme

x2+y2=0  y=-2x2           A1


[1 mark]

a.i.

y=-2x2 drawn on diagram (correct shape with a maximum at (0,0))        A1


[1 mark]

a.ii.

correct shape with a local maximum and minimum, passing through (0, 2)         A1

local maximum and minimum on the graph of y=-2x2         A1


[2 marks]

b.

Examiners report

This question was very poorly done and frequently left blank. Few candidates understood the connection between the differential equation and maximum and minimum points. Even when the equation dydx=0 was correctly solved, it was rare to see the curve correctly drawn on the slope field. Some were able to draw a solution to the differential equation on the slope field though often not through the given initial condition.

a.i.
[N/A]
a.ii.
[N/A]
b.

Syllabus sections

Topic 5—Calculus » AHL 5.15—Slope fields
Topic 5—Calculus

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