Question

x²-x-2=0 x²-8x+12=0 x²+2=3x x²+4x=21

要用因式分解法解方程！！要过程...谢谢！！！

Answer 1

x²-x-2=0
(x+1)(x-2)=0
x=2 或x= -1

x²-8x+12=0
（x-2）（x-6）=0
x=2或 x=6

x²+2=3x
x²-3x+2=0
（x-1）（x-2）=0
x=1或x=2

x²+4x=21
x²+4x-21=0
(x+7)(x-3)=0
x=3或x=-7

Answer 2

x²-x-2=0
(x-2)(x+1)=0
x=2,x=-1

x²-8x+12=0
(x-2)(x-6)=0
x=2,x=6

x²+2=3x
(x-1)(x-2)=0
x=1,x=2

x²+4x=21
(x-3)(x+7)=0
x=3,x=-7

Answer 3

(x-2)(x+1)=0
(x-2)(x-6)=0
(x-1)(x-2)=0
(x-3)(x+7)=0