Question

Решить систему уравнения методом сложения. Пожалуйста

Answer 1

$\displaystyle\bf\\\left \{ {{(2x+1)^{2}-( 2x-y)(2x+y)=(y+8)(y-10)} \atop {4x(x-5)-(2x-3)(2x-9)=6y-104}} \right. \\\\\\\left \{ {{4x^{2} +4x+1-4x^{2} +y^{2} =y^{2} -10y+8y-80} \atop {4x^{2} -20x-4x^{2}+18x+6x-27=6y-104 }} \right. \\\\\\\left \{ {{4x+2y=-81} \atop {4x-6y=-131 \ |\cdot (-1)}} \right. \\\\\\+\left \{ {{4x+2y=-81} \atop {-4x+6y=131}} \right.\\-----------\\8y=50\\\\y=6,25\\\\4x=-2y-81=-2\cdot6,25-81=-12,5-81=-93,5\\\\x=-23,375\\\\Otvet: \ (-23,375 \ ; \ 6,25)$