问题
解答题
用适当的方法解下列方程: (1) x2-5x-6=0; (2) (1-x)2-1=
(3) 8x(x+2)=3x+6; (4)(y+
|
答案
(1)x2-5x-6=0,
(x-6)(x+1)=0,
∴x1=6,x2=-1.
(2) (1-x)2-1=
,21 100
(1-x)2=
+1,21 100
(1-x)2=
,121 100
1-x=±
,11 10
∴x1=1-
=-11 10
,1 10
x2=1+
=11 10
.21 10
(3) 8x(x+2)=3x+6,
8x(x+2)-3(x+2)=0,
(x+2)(8x-3)=0,
∴x1=-2,x2=
.3 8
(4)(y+
) (y-5
) =20.5
y2-5=20,
y2=25,
y=±5,
即 y1=5,y2=-5.