is problem number 1 correct

Question

Problem #1
factor completely. x^4 + x^3 -12

MY answer: (x^2-3)(x^2+4) or is this still factorable.

Problem #2

i need someone to help me set it up for me to solve.

If the sides of a square are decreased by 3cm, the area is decreased by 81 cm^2.What were the dimensions of the original square?

No, you do not have it factored. How did the x cubed term get there? If the x^3 term should be x^2, then it is correct.

(x-3)^2=x^2-81
solve for x.

sorry typo it should read as

x^4+x^2-12