Đáp án:
8) x=4
Giải thích các bước giải:
\(\begin{array}{l}
1)x + 7 = 3x - 4\\
\to 2x = 11\\
\to x = \dfrac{{11}}{2}\\
2)2x - 6 = 7x - 5\\
\to 5x = - 1\\
\to x = - \dfrac{1}{5}\\
3)4x - 2 = 5x - 1\\
\to x = - 1\\
4)5x + 2 = 8x - 6\\
\to 3x = 8\\
\to x = \dfrac{8}{3}\\
5)7x - 4 = 10x + 8\\
\to 3x = - 12\\
\to x = - 4\\
6)2x + 6 = 3x - 21\\
\to x = - 27\\
7)5x - 10 = 2x + 8\\
\to 3x = 18\\
\to x = 6\\
8)6x - 6 = 3x + 6\\
\to 3x = 12\\
\to x = 4\\
9)7 + 3x - 12 = 9 - 2x - 10\\
\to 5x = 4\\
\to x = \dfrac{4}{5}\\
10)20 - 4x - 8 = 36 + 2x - 8\\
\to 6x = - 16\\
\to x = - \dfrac{8}{3}\\
11)13 + 5x - 35 = 60 - x + 8\\
\to 6x = 90\\
\to x = 15\\
12)50 - 10x + 120 = 80 - 7x - 42\\
\to 3x = 132\\
\to x = 44\\
13)5x + 40 + 20 = 6x + 42 - 60\\
\to x = 78\\
14)7x - 63 + 11 = 15x - 150 - 100\\
\to 8x = 198\\
\to x = \dfrac{{99}}{4}\\
15)20x - 300 + 15 = 10x - 90 + 60\\
\to 10x = 255\\
\to x = \dfrac{{51}}{2}
\end{array}\)
