✔ 最佳答案
|x+2|<|2x-4|-1
Sol
x+2=0 =>x=-2
2x-4=0 =>x=2
(1) x<=-2
x+2<=0
|x+2|=-x-2
2x<=-4
2x-4<=-8
|2x-4|=-2x+4
|x+2|<|2x-4|-1
-x-2<-2x+4-1
x<5
So
x<=-2……………….
(2) -2<=x<=2
0<=x+2
|x+2|=x+2
2x<=4
2x-4<=0
|2x-4|=-2x+4
x+2<-2x+4-1
3x<1
x<1/3
So
-2<=x<1/3…………
(3) 2<=x
|x+2|=x+2
|2x-4|=2x-4
x+2<2x-4-1
7<x
So
x>7………………….
綜合(1)(2)(3)
x<=1/3 or x>7
2012-08-26 16:28:25 補充:
|x+2|+1<|2x-4|
x^2+4x+4+2|x+2|+1<4x^2-16x+16
3x^2-20x+11>2|x+2|
(1) x>=-2
3x^2-20x+11>2x+4
3x^2-22x+7>0
(x-1/3)(x-7)>0
x<1/3 or x>7
-2<=x<1/3 or x>7…………….
(2) x<=-2
3x^2-20x+11>-2x-4
3x^2-18x+15>0
(x-1)(x-5)>0
x<1 or x<5
x<=-2………………………..
綜合(1)(2)
x<1/3 or x>7