Question

Решите систему уравнений:
x^2+2y=6
y=x-1

Answer 1

$\displaystyle \left \{ {{x^2+2y=6} \atop {y=x-1}} \right.\quad \rightarrow \quad x^2+2(x-1)=6\\\\\\x^2+2x-2=6\\\\x^2+2x-8=0\\\\D=4+4\cdot 8=4+32=36\\\\x_1=\frac{-2+6}2=\frac{4}2=2\\\\x_2=\frac{-2-6}2=\frac{-8}2=-4\\\\\\y=x-1\quad \rightarrow \quad y_1=2-1=1\\\\y_2=-4-1=-5\\\\\\\boxed{(2;1),\,\,(-4;-5)}$