does this look correct f(x)=?

Question

(3-5x)^3
______ ,then f(x)=-5(2x+1)

(x^2+x-1)^2

Answer 1

Not clear what you are asking.
If the question is whether
(3-5x)^3 = - 5(2x+1) * (x^2+x-1)^2
is correct, then the answer is: no, it is wrong.
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Answer 2

No, that is wrong.

In the original function, you have an expression with a degree of 3 over an expression with a degree of 4, so there is no way to end up with an expression that has a degree of 1.