Question

Решите систему уравнений (70баллов) см. фото ниже, (любым способом, но желательно подстановкой)

Answer 1

$1) \left \{ {x-2y=0{} \atop {x^2=2y+2x-2}} \right. \left \{ {{x=2y} \atop {(2y)^2-2y-2(2y)+2=0,}} \right. \left \{ {{x=2y} \atop 4y^2-6y+2=0(1)}} \right. \\(1)D=6^2-4\cdot2\cdot4=36-32=4,\\y_1=\frac{6+2}{2\cdot4}=1, y_2=\frac{6-2}{8}=0,5.\\ x_1=2\cdot1=2,x_2=2\cdot0,5=1.\\OTVEt: (2;1), (1; 0,5).$

$2)\left \{ {{x-5y=3} \atop {x^2-25y^2=15}} \right. \left \{ {{x=5y+3} \atop {(5y+3)^2-25y^2=15,}} \right. \left \{ {{x=5y+3} \atop {25y^2+30y+9-25y^2=15}} \right. \\\left \{ {{x=5y+3} \atop {30y=6}} \right. \left \{ {{x=4} \atop {y=\frac{1}{5} }} \right.\\OTVET: (4; \frac{1}{5}).$

$3)\left \{ {{x^2-y^2=21} \atop {x+y=3,}} \right. \left \{ {{(x-y)(x+y)=21} \atop {x+y=3}} \right. \left \{ {{3(x-y)=21} \atop {x+y=3}} \right.\left \{ {{x-y=7} \atop {x+y=3}} \right. \\\left \{ {{x=y+7} \atop {y+7+y=3,}} \right. \left \{ {{x=y+7} \atop {2y=-4}} \right. \left \{ {{x=5.} \atop {y=-2}} \right. \\OTVET: (5; -2)$

Answer 2

Вот, надеюсь помогла)