解不等式lx-1l+lx+2l<5

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解不等式lx-1l+lx+2l<5
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解不等式lx-1l+lx+2l<5
解不等式lx-1l+lx+2l<5

解不等式lx-1l+lx+2l<5
lx-1l+lx+2l<5
(1)当x≥1
x-1+x+2

X小于等于1

(1)x<-2 -> 1-x-(x+2)<5 -> x>-3 -> -3(2)-2= 1-x+x+2<5 -> 3<5 -> 成立 -> -2<=x<=1
(3)x>1 -> x-1+x+2<5 -> x<2 -> 1综上所诉,-3

lx-1+X+2l<5
-5<(x-1+X+2)<5
答案-2<X<3

X<=2

1<x时 =x-1+x+2=2x+1<5 x<2 有 1<x<2
-2<x<1时=1-x+x+2=3<5 有-2<x<1
x<-2时=1-x-x-2=-2x-1<5 -2x<6 -x<3 -3<x 有-3<x<-2

这要分四种情况讨论
(1) x-1+x+2<5 (2)x-1-(x+2)<5 (3)-(x-1)+(x+2)<5 (4)-(x-1)-(x+2)<5
∵2x+1<5 无解 无解 ∵-2x-1<5
∴x<2 ∴x<-3