问题
解答题
解方程:
(1)4(x-3)2+x(x-3)=0
(2)(x+1)(x-3)=5
(3)2x2-10x=3
(4)4x2-8x+1=0(本题要求用配方法,否则不得分)
答案
(1)4(x-3)2+x(x-3)=0,
(x-3)(4x-12+x)=0,
x-3=0,4x-12+x=0,
x1=3,x2=2.4;
(2)(x+1)(x-3)=5,
整理得:x2-2x-8=0,
(x-4)(x+2)=0,
x-4=0,x+2=0,
x1=4,x2=-2;
(3)2x2-10x=3,
2x2-10x-3=0,
b2-4ac=(-10)2-4×2×(-3)=124,
x=
,10± 124 2×2
x1=
,x2=5+ 31 2
;5- 31 2
(4)4x2-8x+1=0,
4x2-8x=-1,
配方:4x2-8x+22=-1+22,
(2x-2)2=3,
开方:2x-2=±
,3
x1=
,x2=2+ 3 2
.2- 3 2