Please confirm: {(5x+2)^4/x^2-3x+1)^3}=
20(5x+2)^2(x^2-3x+1)^3 -3x^2(5x+2)^4 (x^2-3x+1)^2/(x^2-3x+1)^6
There are insufficient parentheses in the question and the answer.
Remember that multiplication and division take precedence over addition and subtraction. So it is mandatory to insert parentheses around numerators and denominators.