Question

因式分解x方-9=2分之1（x方-6x+9）

Answer 1

x^2-9=(x^2-6x+9)/2

2(x^2-9)=(x^2-6x+9)

2(x-3)(x+3)-(x^2-6x+9)=0

2(x-3)(x+3)-(x-3)^2=0

(x-3)[2(x+3)-(x-3)]=0

(x-3)(2x+6-x+3)=0

(x-3)(x+9)=0

x=-3或x=-9