Question

Tìm x, biết:

a. \(\sqrt{x^2}=7;\)

b. \(\sqrt{x^2}=\left|-8\right|;\)

c. \(\sqrt{4x^2}=6;\)

d. \(\sqrt{9x^2}=\left|-12\right|.\)

Answer 1

a, x = 7

b, x = 8

c, x = 3

d, x = 4

Answer 2

a. \(\sqrt{x^2}=7\Leftrightarrow\left|x\right|=7\Leftrightarrow\left[{}\begin{matrix}x=7\\x=-7\end{matrix}\right..\)

b. \(\sqrt{x^2}=\left|-8\right|\Leftrightarrow\left|x\right|=8\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right..\)

c. \(\sqrt{4x^2}=6\Leftrightarrow\left|2x\right|=6\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right..\)

d. \(\sqrt{9x^2}=\left|-12\right|\Leftrightarrow\left|3x\right|=12\Leftrightarrow\left[{}\begin{matrix}3x=12\\3x=-12\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right..\)