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
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.
