Question

2x^2+x-21=-8x^2 помогите пожалуйсто

Answer 1

$2 x^{2} + x - 21 = -8 x^{2} \ 2 x^{2} + 8 x^{2} + x - 21 = 0 \ 10 x^{2} + x - 21 = 0 \ D = 1 + 840 = 841$

$x_{1} = frac{-1+29}{20} = 1,4 \ \ x_{2} = frac{-1-29}{20} = -1.5$