Question 1011

Definite Integrals: Areas and Volumes
2011 Paper 1 Question 5 Variant

Question

It is given that f(x)=3x.{f(x)=3 - x.}
(i)
On separate diagrams, sketch the graphs of y=f(x){y=f(|x|)} and y=f(x),{y=|f(x)|,} giving the coordinates of any points where the graphs meet the x-{x\textrm{-}} and y-{y\textrm{-}}axes. You should label the graphs clearly.
[3]
(ii)
State the set of values of x{x} for which
f(x)=f(x).f(|x|)=|f(x)|.
[1]
(iii)
Find the exact value of the constant a{a} for which
3232f(x)  dx=32af(x)  dx.\int_{- \frac{3}{2}}^{\frac{3}{2}} f(|x|) \; \mathrm{d}x = \int_{\frac{3}{2}}^a |f(x)| \; \mathrm{d}x.
[3]

Answer