题目内容
用因式分解法解下列方程:
(1)3x2+2x=0
(2)x2=3x
(3)x(3x+2)=6(3x+2)
(4)(3x-1)2=(2-x)2
(5)3x2+12x=-12
(6)x2-4x+3=0.
(1)3x2+2x=0
(2)x2=3x
(3)x(3x+2)=6(3x+2)
(4)(3x-1)2=(2-x)2
(5)3x2+12x=-12
(6)x2-4x+3=0.
分析:(1)(6)直接利用因式分解法解方程即可;
(2)(3)(4)(5)先移项,再进一步利用因式分解法解方程.
(2)(3)(4)(5)先移项,再进一步利用因式分解法解方程.
解答:(1)3x2+2x=0
解:x(3x+2)=0
x=0,3x+2=0
x1=0,x2=-
;
(2)x2=3x
解:x2-3x=0
x(x-3)=0
x=0,x-3=0
x1=0,x2=3;
(3)x(3x+2)=6(3x+2)
解:x(3x+2)-6(3x+2)=0
(x-6)(3x+2)=0
x-6=0,3x+2=0
x1=6,x2=-
;
(4)(3x-1)2=(2-x)2
解:(3x-1)2-(2-x)2=0
[(3x-1)+(2-x)][(3x-1)-(2-x)]=0
(2x+1)(4x-3)=0
2x+1=0,4x-3=0
x1=-
,x2=
;
(5)3x2+12x=-12
解:3x2+12x+12=0
3(x+2)2=0
x+2=0
x1=x2=-2;
(6)x2-4x+3=0
解:(x-1)(x-3)=0
x-1=0,x-3=0
x1=1,x2=3.
解:x(3x+2)=0
x=0,3x+2=0
x1=0,x2=-
2 |
3 |
(2)x2=3x
解:x2-3x=0
x(x-3)=0
x=0,x-3=0
x1=0,x2=3;
(3)x(3x+2)=6(3x+2)
解:x(3x+2)-6(3x+2)=0
(x-6)(3x+2)=0
x-6=0,3x+2=0
x1=6,x2=-
2 |
3 |
(4)(3x-1)2=(2-x)2
解:(3x-1)2-(2-x)2=0
[(3x-1)+(2-x)][(3x-1)-(2-x)]=0
(2x+1)(4x-3)=0
2x+1=0,4x-3=0
x1=-
1 |
2 |
3 |
4 |
(5)3x2+12x=-12
解:3x2+12x+12=0
3(x+2)2=0
x+2=0
x1=x2=-2;
(6)x2-4x+3=0
解:(x-1)(x-3)=0
x-1=0,x-3=0
x1=1,x2=3.
点评:此题考查利用因式分解法解方程,注意方程的特点,灵活运用适当的方法因式分解.
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