The function \(\mathrm f\) is defined by \(\mathrm f(x)=2x-1\) for \(x\in\mathbb R\).
Explain why the function \(\mathrm f^2\) can be formed.[1]
On the axes, sketch the graph of \(y=|\mathrm f^2(x)|\).
State any intercepts with the coordinate axes.[4]
It is given that \(|\mathrm f^2(x)|\le ax+b\) for \(-1\le x\le3\) and for no other values of \(x\).
Find the values of \(a\) and \(b\).[3]