Question

bài 3 : Tìm x biết:

a) x+15=-7

b) ( 5x -2).8 mũ 3 = 8 mũ 4

c) |x-1| = 2

Answer 1

a)x+15=-7

x=(-7)-15

x=-22

b)\(\left(5x-2\right).8^3=8^4\)

(5x-2).512=4096

(5x-2)=4096:512

(5x-2)=8

5x=8+2

5x=10

x=10:5

x=2

c)|x-1|=2

=>x-1=2      hoac   x-1=-2

x=2+1                    x=-2+1

                             

x=3                          x=-1

Answer 2

a/ => x = (-7) - 15 = -22

Vậy x = -22

b/ (5x - 2) . 8³ = 8⁴

=> 5x - 2 = 8

=> 5x = 10

=> x = 2

Vậy x = 2

c/ => x - 1 = 2 => x = 3

hoặc x - 1 = -2 => x = -1

Vậy x = 3 ; x = -1