Question

Tìm X

a) -3(7-x)-5(2x+1)=-(x+2)

b) (x-1)²=4

Answer 1

a. -3(7-x)-5(2x+1)=-(x+2)

<=> -21 + 3x -10x -5 =-x-2

<=> 3x-10x+x=21+5-2

<=> -6x=24

<=> x=-4

Vậy ...

b. \(\left(x-1\right)^2=4\Leftrightarrow\left[{}\begin{matrix}\left(x-1\right)^2=2^2\\\left(x-1\right)^2=\left(-2\right)^2\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=2\\x-1=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)

Vậy ...