用适当的方法解下列方程(1)4(x-3) 2 -25=0(2)x(x-4)=3(4-x)(3)(2x+1) 2 -5(2x+1)-6=0(4

2024-11-16 11:44:59
推荐回答(1个)
回答(1):

(1)4(x-3) 2 =25
x-3=±
5
2

x=3±
5
2

∴x 1 =
11
2
,x 2 =
1
2

(2)(x-4)(x+3)=0
∴x 1 =4,x 2 =-3.
(3)(2x+1-6)(2x+1+1)=0
(2x-5)(2x+2)=0
∴x 1 =
5
2
,x 2 =-1.
(4)方程整理得:
x 2 -4x-1=0
a=1,b=-4,c=-1,
△=16+4=20
x=
20
2

∴x 1 =2+
5
,x 2 =2-
5