I understand that a vertical stretch, ie a stretch on y axis is y = af(x) and a horizontal stretch, ie a stretch on the x axis is y=f(ax).
and eg y=2sinx is an example of a vertical stretch and y=sin 2x is an example of a horizontal stretch. That's fine.
But if I apply to a really simple example, eg y=x^2, then a vertical stretch would be:
y=2x^2? Is that correct?
But for a horizontal stretch y=(2x)^2?