a) \(-3x+5=41\)
\(\Leftrightarrow-3x=41-5\)
\(\Leftrightarrow3x=-36\)
\(\Leftrightarrow x=-\dfrac{36}{3}=-12\)
Vậy \(x=-12\)
b) \(52-\left|x\right|=80\)
\(\Leftrightarrow\left[{}\begin{matrix}52-x=80\\52+x=80\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-28\\x=28\end{matrix}\right.\)
Vậy \(x=\pm28\)
c) \(\left|7x+1\right|=20\)
\(\Leftrightarrow\left[{}\begin{matrix}7x+1=20\\7x+1=-20\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{19}{7}\\x=-\dfrac{21}{7}=-3\end{matrix}\right.\)
Vậy \(\left[{}\begin{matrix}x=\dfrac{19}{7}\\x=-3\end{matrix}\right.\)
a, -3x + 5 = 41
-3x = 41 - 5
-3x = 36
x = 36 : -3
x = -12
b, 52 - |x| = 80
| x | = 52 - 80
|x| = -28
Mà giá trị tuyệt đối ko thể là số âm nên x thuộc rỗng
|7x + 1 | = 20
+ 7x + 1 = 20 hoặc + 7x + 1 = -20
+ 7x + 1 = 20
7x = 20 - 1
7x = 19
x = 19 : 7
x = \(\dfrac{19}{7}\)
+7x + 1 = -20
7x = -20 - 1
7x = -21
x = -21 : 7
x = -3
vậy x = \(\dfrac{19}{7}\) hoặc x = -3
