:write 3x^2(-5x^2 - 2x^2) in standard form

3x^2(-5x^2-2x^2)
-15x^4-6x^4
-21x^4

I believe this is right. Not too sure. But I hope it helped a bit.

Okay so I just learned this too. So basically what you want to do is first plug in the 5 only then after you solve after plugging that in rewrite the equation but plug in the -7. If that makes sense. If it doesnt ask me again in the comments to explain more differently