1) 20x²+x-1=0 2) 8x²+10x+3=0 3)-6x²+7-2=0

20x²+x-1=0 д=b^2-4ac=1^2-4*20*(-1)=81 = 9^2 x1=(-1-9)\40=-1\4  x2=(-1+9)\40=1\5 ----------------------------------------------- 8x²+10x+3=0 д=4=2^2 x1,2=(-10+-2)\16=-1\2; -3\4 ----------------------------------------------- -6x²+7-2=0  -6x^2=-7+2 -6x^2=-5 6x^2=5 x^2=5\6 x1=[latex] -\sqrt{ \frac{5}{6} } [/latex]  [latex] x2=\sqrt{ \frac{5}{6} } [/latex]