Advanced difference of two squares

The images the bottom question is the one I’m stuck on

I can’t seem to upload the question and my working so I’ll type it

[(2x+y)(y-2x)]^2-(4x^2+y^2+2z^2)^2

I noticed it was dots and I expanded the first bracket twice and the second once.

Is there a quicker way of doing this and will it come up in the exam. I think this is very tedious

Ps can someone help me upload images on tar iOS because it asks me to use a link but when I had my android I could take a pic and show it

The first bracket gives
(y^2-4x^2)^2
Then its simply doing dots as usual so
(sum)(difference)
and you pretty much write down the answer. Should be two (at most three) simple lines.

Theres the "new tsr" thread for reporting problems with it.

I still don’t get it can you show me?
It’s not homework it’s from the cgp textbook

Dots is
a^2 - b^2 = (a+b)(a-b)
so here a=(y^2-4x^2) and b=(4x^2+y^2+2z^2). So ...

Obv in a+b the 4x^2 term disappears and in the a-b, the y^2 term disappears.