tìm số nguyên x, biết: a) |x-2|=3 b) |x+2|=3 c) |x+2|=x+2 d) |x-2|=2-x e) |x-1|=3 g) |x-12|=-1

a, |x-2| = 3

* TH1:

x-2 = 3  (x>2)

 x = 5

*TH2:

x-2 = -3

x= -1

b) |x+2|=3

*TH1: (x> -2)

x+2 = 3

x = 1

*TH2: (x< -2)

x+2 = -3

x = -5

c) |x+2|=x+2

*TH1: (x>-2)

x+2 = -(x+2)

x+2 = -x-2

2x = -4

x = -2

d) |x-2|=2-x

*TH1: (x>2)

x-2 = 2-x

2x = 4

x = 2

*TH2: (x<2)

x-2 = -(2-x)

x-2 = -2 +x

0x =0

x = 0

e) |x-1|=3

*TH1: (x>1)

x-1 = 3

x = 4

*TH2: (x<1)

x-1 = -3

x = -2

g) |x-12|=-1

*TH1: (x>12)

x-12 = -1

x = 11

*TH2: (x<12)

x-12 = 1

x = 13

Trả lời