Question

решить уравнение 3х^2-х+21=5х^2

Answer 1

3x² - x + 21 = 5x²
2x² + x - 21 = 0
D = 1² - 4 * 2 * (- 21) = 1 + 168 = 169 = 13²
$X _{1} = \frac{-1+13}{4}= \frac{12}{4} =3\\\\X _{2}= \frac{-1-13}{4}=- \frac{14}{4}=-3,5$