4.25. 5x² − 8x − 4 = 0

Question

Дискриминант: \(D=(-8)^2-4\cdot5\cdot(-4)=144\), \(\sqrt D=12\).

\(x=\frac{8\pm12}{10}\).

\(x_1=\frac{8+12}{10}=2\), \(x_2=\frac{8-12}{10}=-\frac25\).

Ответ: \(x_1=2\), \(x_2=-\frac25\).

Accepted Answer

Дискриминант: \(D=(-8)^2-4\cdot5\cdot(-4)=144\), \(\sqrt D=12\).

\(x=\frac{8\pm12}{10}\).

\(x_1=\frac{8+12}{10}=2\), \(x_2=\frac{8-12}{10}=-\frac25\).

Ответ: \(x_1=2\), \(x_2=-\frac25\).