Đáp án:
Giải thích các bước giải:
a, 44 - ( 24 - 2x)= -3x + 65
44 - 24 + 2x = -3x + 65
2x + 3x = 65 + 24 - 44
5x = 45
x =9
b, ( 3 x - 12) - ( 2x + 31 ) = -11
3x - 12 - 2x - 32 = -11
3x - 2x = -11 + 32 + 12
x = 33
c, / -21 / + / x-12 / = 51
21 + / x-12 / = 51
/ x- 12 / = 30
\(\left[ \begin{array}{l}x-12=30\\x-12=-30\end{array} \right.\)
\(\left[ \begin{array}{l}x=32\\x=-18\end{array} \right.\)
d, ( x+ 3 ) ³ : 3 -1 = -10
(x + 3 ) ³ : 3 = -9
(x+3)³ = -27
=) x+3 = -3
x =-6
e, -2 ( x+ 7 ) + 5 ( x-2 ) = x-12
-2x - 14 + 5x -10 = x -12
-2x + 5x - x = -12 + 10 + 14
2x = 12
x=6