1.Tính nhanh
a)(-75).123+25.(-123)
b)135.17+35.(-17)
c)125.(-61).(-2)^3.(-1)^4
d)136.(-47)+36.47
e)(-48).72+36.(-304)
2.Tìm x ∈ Z bt
a) -3x+5=41
b) 52+lxl=80
c)l2x+6l=20
3.Tìm x bt
a) -12.(x-5)+7.(3-x)=5
b)30.(x+2)-6(x-5)-24x=100
5.Tìm x;y bt
a) (x-3).(2y)+1)=7
b) (2x+1).(3y-2)= -56
