Question

Решите уравнение.
2x^2+x−21=−8x^2

Answer 1

$2x^2+x-21=-8x^2 \ 2x^2+x-21+8x^2=0 \ 10x^2+x-21=0 \ x= frac{-1+- sqrt{1^2-4*10(-21)} }{2*10} \ x= frac{-1+- sqrt{1+840} }{20} \ x= frac{-1+- sqrt{841} }{20} \ x= frac{-1+-29}{20} \ left[begin{array}{ccc}x= frac{-1+29}{20} \ x= frac{-1-29}{20} end] \ left[begin{array}{ccc}x= frac{7}{5} \ x= -frac{3}{2} end]$