Question

tính x

\(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\)

Answer 1

Ta có: \(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\)

\(\Leftrightarrow x\cdot\left(-x\right)=-2\cdot\frac{8}{25}=\frac{-16}{25}\)

\(\Leftrightarrow-x^2=-\frac{16}{25}\)

\(\Leftrightarrow x^2=\frac{16}{25}\)

\(\Leftrightarrow x\in\left\{\frac{4}{5};\frac{-4}{5}\right\}\)

Vậy: \(x\in\left\{\frac{4}{5};\frac{-4}{5}\right\}\)

Answer 2

theo đề ta có

2 x 0,32 = -(x)²

<=>-(x)² = 0,64

<=>-x = \(\sqrt{0,64}\)

<=> x = -\(\sqrt{0,64}\)

Answer 3

=> \(-2\times\frac{8}{25}=-x^2\)

=> \(-x^2=\frac{-16}{25}\)

=> \(x^2=\frac{16}{25}\)

=> \(x=\frac{4}{5}\)

Vậy \(x=\frac{4}{5}\)