Câu hỏi của MonkeyDace

Question

giup mik

(-2)²-2x²=-50

2/x/-5/x/=-9

giup mik nhe

Nguyễn Xuân Anh · Accepted Answer

a, $\left(-2\right)^2-2x^2=-50.$

$\Leftrightarrow4-2x^2=-50$

$\Leftrightarrow2x^2-54=0$

$\Leftrightarrow x^2-27=0$

$\Leftrightarrow\left(x-3\sqrt{3}\right)\left(x+3\sqrt{3}\right)=0$

$\Leftrightarrow\orbr{\begin{cases}x=3\sqrt{3}\x=-3\sqrt{3}\end{cases}}$

Câu trả lời:

a, $\left(-2\right)^2-2x^2=-50.$

$\Leftrightarrow4-2x^2=-50$

$\Leftrightarrow2x^2-54=0$

$\Leftrightarrow x^2-27=0$

$\Leftrightarrow\left(x-3\sqrt{3}\right)\left(x+3\sqrt{3}\right)=0$

$\Leftrightarrow\orbr{\begin{cases}x=3\sqrt{3}\x=-3\sqrt{3}\end{cases}}$

Siêu Phẩm Hacker · Answer

$\left(-2\right)^2-2x^2=-50$

$\Leftrightarrow x^2=\frac{-50-\left(-2\right)^2}{-2}$

$\Leftrightarrow x^2=27$

$\Leftrightarrow x=\pm\sqrt{27}$

$\Leftrightarrow x=\pm3\sqrt{3}$

$\frac{2}{x}-\frac{5}{x}=-9$

$\Leftrightarrow\frac{2-5}{x}=-9$

$\Leftrightarrow-3=-9x$

$\Leftrightarrow x=\frac{-3}{-9}=\frac{1}{3}$