Factor and check: x^2 + 0x - 81 = 0

x^2 + 0x - 81 = 0

(x )(x ) ( -9)( +9)=0

(x-9) (x+9) = 0

Check:

(x-9) (x+9) = 0

(x)(x) (x)(9) (-9)(x) (-9)(9)=0

x^2 +9x -9x -81=0

x^2 0x -81=0