Question

Решите пожалуйста 1 и 5 задание!!)))
Срочно

Answer 1

$1)\left \{ {{x^{2}-y^{2}=-5} \atop {y+x=1}} \right.\\\\\left \{ {{(x+y)(x-y)=-5} \atop {x+y=1}} \right.\\\\+\left \{ {{x-y=-5} \atop {x+y=1}} \right. \\\\------\\2x=-4\\\\x=-2\\\\y=1-x=1-(-2)=1+2=3\\\\Otvet:\boxed{(-2;3)}$

$5)\left \{ {{x^{2}+3xy=18 } \atop {x-y=2}} \right. \\\\\left \{ {{y=x-2} \atop {x^{2}+3x*(x-2)=18 }} \right.\\\\\left \{ {{y=x-2} \atop {x^{2}+3x^{2}-6x-18=0}} \right. \\\\\left \{ {{y=x-2} \atop {4x^{2}-6x-18=0 }} \right.\\\\\left \{ {{y=x-2} \atop {2x^{2}-3x-9=0}} \right.\\\\2x^{2}-3x-9=0\\\\D=(-3)^{2}-4*2*(-9)=9+72=81=9^{2}\\\\x_{1} =\frac{3-9}{4}=-1,5\\\\x_{2}=\frac{3+9}{4}=3\\\\y_{1} =-1,5-2=-3,5\\\\y_{2}=3-2=1 \\\\Otvet:\boxed{(-1,5;-3,5),(3;1)}$