Đáp án:
câu 1)
ta có X > Y suy ra -11X < -11Y suy ra -11X+5 < -11Y+5
2)
a) X+1>0 suy ra X>-1
b)-2X+8≤0 suy ra -2X≤-8 suy ra X≥4
c)-3X-1≥9+2X suy ra -5X≥10 suy ra X ≤ -2
d)(3X-5)/2<(7-X)/3 suy ra (3X-5)*3<(7-X)*2 suy ra 9X-15<14-2X
suy ra 11X<29 suy ra X<29/11
câu 3)
a) l X+3 l = 3X -5
<=> X+3=3X-5 hay X+3=-3X+5
<=> X = 4 hay X = -0,5
b) l 3X l = -2X +1
<=> 3X=-2X+1 hay 3X=2X-1
<=> X=0,2 hay X=-1
