\(\left|x\right|+\left|-12\right|=\left|-42\right|\)
\(\left|x\right|+12=42\)
\(\left|x\right|=42-12=30\)
\(\Rightarrow\orbr{\begin{cases}x=30\\x=-30\end{cases}}\)
vậy ,,,
b) \(\left|-8\right|.\left|x\right|=\left|-56\right|\)
\(8.\left|x\right|=56\)
\(\left|x\right|=\frac{56}{8}=7\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)
vậy ..
a /x/ +12 =42
/x/ = 42-12
/x/ = 30
suy ra x=30 hoặc x=-30
vậy x=30, x=-30
b /-8/./x/ =/-56/
8./x/ = 56
/x/ = 7
suy ra x=7 hoặc x=-7
vậy x=7, x=-7