Question

решить уравнения : а)2*(5х+7)*(1+х)=0
б)3х в квадрате + 2х-5=0

Answer 1

$1)2(5x+7)(1+x)=0\(10x+14)(1+x)=0\10x+14=0\10x=-14\x=- frac{14}{10} \ x=-1.4 \ \ 1+x=0\x=-1$

$3 x^{2} +2x-5=0\D=4+60=64\ sqrt{D} =8 \ x_{1} = frac{-2+8}{6} = frac{6}{6} =1 \ \ x_{2} = frac{-2-8}{6} =- frac{10}{6} =- frac{5}{3} =-1 frac{2}{3}$