x^2+18x+81
(x+9)^2
2x^2-8x+8
2(x-2)^2
3x^2-12x+12
3(x-2)^2
5x^2+30x+45
5(x+3)^2
-5x^2+20
-5(x-2)(x+2)
-3x^2+18x-27
-3(x-3)^2
25x^2-30x+9
(5x-3)^2