问题
解答题
解方程:
(1)(2x+1)2=3
(2)x2+2x-24=0
(3)2x2-4x+5=0
(4)4x2+4x+10=1-8x
(5)9x2+6x+1=0
(6)x2-5x-14=0.
答案
(1)(2x+1)2=3,
2x+1=±
,3
解得:x1=
,x2=-1+ 3 2
;-1- 3 2
(2)x2+2x-24=0,
(x+6)(x-4)=0,
解得:x1=-6,x2=4;
(3)2x2-4x+5=0
∵b 2-4ac=16-4×2×5=-24<0,
∴此方程没有实数根;
(4)4x2+4x+10=1-8x,
整理得:4x2+12x+9=0,
(2x+3) 2=0,
解得:x1=x2=-
;3 2
(5)9x2+6x+1=0,
(3x+1) 2=0,
解得:x1=x2=-
;1 3
(6)x2-5x-14=0,
(x-7)(x+2)=0,
解得:x1=7,x2=-2.