Question

Решите систему не линейных уравнений
xy=-30
x+y=1

Answer 1

$\left\{{{xy=-30}\atop{x+y=1}}\right.\\\\\left\{{{xy=-30}\atop{y=1-x}}\right.\\\\x*(1-x)=-30\\\\x^2-x-30=0\\\\D=1-4*1*(-30)=1+120=121=11^2\\\\x_1=\frac{1-11}{2}=-5\\\\x_2=\frac{1+11}{2}=6\\\\x_1=-5=>y_1=1-(-5)=6\\\\x_2=6=>y_2=1-6=-5$