Question

Решить систему уравнений {x^2+xy-y^2=11. {x-2y+1=0

Answer 1

$begin{cases}x^2+xy-y^2=11\x-2y+1=0end{cases}\begin{cases}(x-2y)^2+5xy=11\x-2y=-1end{cases}\begin{cases}5xy=10\x-2y=-1end{cases}\x=cfrac{2}{y}\cfrac{2}{y}-2y=-1\2-2y^2+y=0\2y^2-y-2=0\D=1+16=17\y=cfrac{1pmsqrt{17}}{4}\x=cfrac{8}{1pmsqrt{17}}$