So I am doing my algebra home work and I get stuck on these three problems.

Question

x^2-19x+72 from there idk what to do because nothing multiplies up to 72 and adds up to -19.

Same for this one.
x^2-25x+48

And
x^2+9-90
(X+15) (x-6)

Answer 1

x^2 -19x + 72
Prime
x^2 -25x +48
prime

Or you can use quadratic formula

ok
(x -6)(x+15)