Question

Нужна в решении уравнения. 5х во второй степени +4х-20=0

Answer 1

5x² + 4x - 20 = 0
D = b² - 4ac = 4² - 4 * 5 * (-20) = 416 > 0

$x_1= \frac{-b- \sqrt{d}}{2a}= \frac{-4- \sqrt{416}}{2 * 5}= \frac{-4-4 \sqrt{26}}{10}= \frac{-4(1+ \sqrt{26})}{10}= \frac{-2(1+ \sqrt{26})}{5} \\ \\ \\ x_2= \frac{-b+ \sqrt{d}}{2a}= \frac{-4+ \sqrt{416}}{2 * 5}= \frac{-4+4 \sqrt{26}}{10}= \frac{-4(1- \sqrt{26})}{10}= \frac{-2(1- \sqrt{26})}{5}$