Question

Tìm số nguyên \(x\), biết :

a) \(2\left|x+1\right|=10\)

b) \(\left(-12\right)^2x=56+10.13x\)

Answer 1

a) 2|x+1|=10

\(\left|x+1\right|\) = 10:2

\(\left|x+1\right|\) = 5

\(\left[{}\begin{matrix}x+1=5\\x+1=-5\end{matrix}\right.\) \(\Rightarrow\) \(\left[{}\begin{matrix}x=5-1\\x=\left(-5\right)-1\end{matrix}\right.\) \(\Rightarrow\) \(\left[{}\begin{matrix}x=4\\x=-6\end{matrix}\right.\)

b) (−12)2x=56+10.13x

144x= 56+130x

144x-130x= 56

14x= 56

x= 56: 14

x= 4

Answer 2

a) 2\(|\)x + 1\(|\) = 10 \(\Rightarrow\) \(|\)x + 1\(|\) = 5

\(\Rightarrow\) x + 1 = 5 hay x = 4

hoặc x + 1 = \(-\)5 hay x = \(-\)6.

ĐS : x = 4, x = \(-\)6.

b) x = 4.