解方程:
(1)(x+1)2-9=0
(2)x2-12x-4=0
(3)3(x-2)2=x(x-2)
【答案】
分析:(1)分解因式得出(x+1+3)x+1-3)=0,推出x+1+3=0,x+1-3=0,求出方程的解即可;
(2)移項(xiàng)后配方得出(x-6)
2=40,開(kāi)方得出x-6=±
,求出即可;
(3)移項(xiàng)后分解因式得出(x-2)(2x-6)=0,推出x-2=0,2x-6=0,求出即可.
解答:解:(1)(x+1)
2-9=0,
分解因式得:(x+1+3)x+1-3)=0,
x+1+3=0,x+1-3=0,
解得:x
1=-4,x
2=2.
(2)x
2-12x-4=0
移項(xiàng)得:x
2-12x=4,
配方得:x
2-12x+6
2=4+6
2,
(x-6)
2=40,
開(kāi)方得:x-6=±
,
x
1=6+2
,x
2=6-2
.
(3)3(x-2)
2=x(x-2),
移項(xiàng)得:3(x-2)
2-x(x-2)=0,
分解因式得:(x-2)[3(x-2)-x]=0,
(x-2)(2x-6)=0
x-2=0,2x-6=0,
解得:x
1=2,x
2=3.
點(diǎn)評(píng):本題考查了解一元二次方程,解此題的關(guān)鍵是能選擇適當(dāng)?shù)姆椒ń庖辉畏匠蹋?