Question

Bài 1 : Tìm x biết :

a, 15+(32-2x)=65

b, 18.(x-5) mu 2 = 72

c, | 19-x|-6=0

Bài 2 : Tìm số nguyên x biết :

a, 20 + 2 mũ 3 . x = 5 mũ 2 . 4

b, ( 2x + 7) chia hết cho ( x+ 2)

Answer 1

bài 1

a) \(15+\left(32-2x\right)=65\)

\(32-2x=65-15\)

\(32-2x=50\)

\(2x=32-50\)

\(2x=-18\)

\(x=-18:2\)

\(x=-9\)

vậy \(x=-9\)

b)\(18.\left(x-5\right)^2=72\)

\(\left(x-5\right)^2=72:18\)

\(\left(x-5\right)^2=4=2^2\)

\(x-5=2\)

\(x=2+5=7\)

vậy \(x=7\)

c)\(\left|19-x\right|-6=0\)

\(\left|19-x\right|=0+6=6\)

\(19-x=\pm6\)

\(\left[{}\begin{matrix}19-x=6\\19-x=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=13\\x=25\end{matrix}\right.\)

vậy \(x\in\left\{13;25\right\}\)