Question

[thục hà]

tìm x biết

a, -12.(x-5) +7 . (3-x) = 5

b, 30.(x+2) - 6 .(x-5) - 24.x = 100

c, | 2x-5| = 13

d, (x+1) + ( x+3) + (x+5) +.....+(x+99) = 0 

Answer 1

[Kuriyama Mirai]

 -12.(x - 5) + 7.(3 - x) = 5

-12x + 60 + 21 - 7x = 5

-12x - 7x = 5 - 60 - 21

-19x = -76

x = -76 : (-19)

x = 4

Vậy x = 4