x²+x-20=0
a=1; b=1; c=-20
D=b²-4ac
D=1²-4×1×(-20)=1-(-80)=1+80=81
x1=-b-√D/2a=-1-√81/2×1=-1-9/2=-10/2=-5
x2=-b+√D/2a=-1+√81/2×1=-1+9/2=8/2=4
ответ: -5; 4
