1) 5.(x-3)-2.(x+6)=9
<=> 5x - 15 - (2x+12) =9
⇔ 5x -15 - 2x - 12 - 9 = 0
⇔ 3x - 36 = 0
⇔ 3 (x-12) = 0
⇔ x = 12
Vậy x=12
2)5.(x-7)+10(5-x)=20
⇔5x - 35 + 50 - 10x = 20
⇔-5x + 15 = 20
⇔-5x = 20-15 = 5
⇔ x = -1
Vậy x=-1
3)-4.(x+1)+8(x-3)=24
⇔-4x - 4 + 8x - 24 = 24
⇔ 4x - 28 = 24
⇔ 4x = 24+28 = 52
⇔ x = 13
Vậy x = 13
4)7(5x)+5(x-2)=15
⇔ 35x + 5x - 10 = 15
⇔ 40x = 15 + 10 = 25
⇔ x = $\frac{5}{8}$
vậy x = $\frac{5}{8}$
5)4(x-1)-3(x-2)=-/-5/
⇔ 4x - 4 - 3x + 6 = -(-5) = 5
⇔ x + 2 = 5
⇔ x = 3
Vậy x = 3
