what is the third term necessary to make this a perfect square trinomial?

Question

what is the binomial quantity squared it is equivalent to?

x^2 - 9x _______= (________)^2

x^2 + 10x _______= (________)^2

Answer 1

since (a-b)^2 = a^2-2ab+b^2, just divide the middle coefficient by 2 and square it.

(9/2)^2

and

5^2