a/ |x| > x => |x| - x > 0
+) khi x > 0 => x - x > 0 => 0x > 0 (vô lí)
+) Khi x < 0 => -x - x > 0 => -2x > 0 => x < 0
b/ |x| < x => |x| - x < 0
+) khi x > 0 => x - x < 0 => 0x < 0 (vô lí)
+) Khi x > 0 => -x - x < 0 => -2x < 0 => x > 0
a/[x-2][7-x] > 0 . tim x thuoc Z
b/[x mu 2+13][x mu 2-17] > 0 . tim x thuoc Z
c/[x mu 2-13][x mu 2-17] <0 . tim x thuoc Z
GIUP MINH VOI
NGAY KIA MINH DI BOI DUONG ROI
CAM ON CAC BAN NEU CAC BAB GIUP MINH
cho bieu thuc: M=x^2-5 phan x^2 (x thuoc Z)
Tim x thuoc Z de M co gia tri nguyen
tim x, y, z thuoc Z sao cho /x-y/+/y-z/+/x-z/=2019
1 )Tim x, y thuoc Z
x + y = x.y
2) Tim x thuoc Z
(x + 1)+(x+3)+(x+5)+...+(x+99)=0(x-3)+(x-2)+(x-1)+...+10+11=11-12(x-5)+7(3-x)=530(x+2)-6(x-5)-24x=100tim x, y thuoc z biet :
/ x-y / + / y-z/ + /z - x / = 2015
tim x thuoc z ,biet x+(x+1)+(x+2) +...+(x+30)=1240
Tim x thuoc Z: (x+1)+(x+2)+(x+3)+...+(x+40)=1000
tim x thuoc z biet x+5:x-2
Tim x thuoc Z sao cho x. |x| = -1
tim x, y, z thuoc Z sao cho /x-y/+/y-z/+/z-x/=2019
