Question

Tìm x, biết:

a) 2 . ( x - 5 ) - 17 = 25

b) 3 . ( x + 7 ) - 15 = 27

Answer 1

a) 2 . ( x - 5 ) - 17 = 25

=> 2(x - 5) = 25 + 17

=> 2(x - 5) = 42

=> x - 5 = 42 / 2

=> x - 5 = 21

=> x = 21 + 5 = 26

b) 3 . ( x + 7 ) - 15 = 27

=> 3(x + 7) = 27 + 15

=> 3(x + 7) = 42

=> x + 7 = 42 / 3

=> x + 7 = 14

=> x = 14 - 7 = 7

 

Answer 2

a) \(\text{2 . ( x - 5 ) - 17 = 25}\)

\(\text{=> 2 . ( x - 5 ) = 25 + 17}\)

\(\text{=> 2 . ( x - 5 ) = 42}\)

\(\text{=> x - 5 = 42 : 2}\)

\(\text{=> x - 5 = 21}\)

\(\text{=> x = 21 + 5}\)

\(\text{=> x = 26}\)

Vậy x = 26.

b) \(\text{3 . ( x + 7 ) - 15 = 27}\)

\(\text{=> 3 . ( x + 7 ) = 27 + 15}\)

\(\text{=> 3 . ( x + 7 ) = 42}\)

\(\text{=> x + 7 = 42 : 3}\)

\(\text{=> x + 7 = 14}\)

\(\text{=> x = 7}\)

Vậy x = 7.