Question

Люди добрые помогите пожалуйста неделю не могу решить никак не пойму..
развязать систему с методом додавания:​

Answer 1

$\displaystyle\bf\\1)\\\\+\left \{ {{3y-2xy=9} \atop {x+2xy=5}} \right. \\---------\\x+3y=14\\\\x=14-3y\\\\3y-2y\cdot(14-3y)=9\\\\3y-28y+6y^{2} -9=0\\\\6y^{2} -25y-9=0\\\\D=(-25)^{2} -4\cdot 6\cdot(-9)=625+216=841=29^{2} \\\\\\y_{1} =\frac{25-29}{12} =-\frac{4}{12} =-\frac{1}{3} \\\\\\y_{2} =\frac{25+29}{12} =\frac{54}{12} =4,5\\\\\\x_{1} =14-3\cdot\Big(-\frac{1}{3} \Big)=14+1=15\\\\x_{2} =14-3\cdot 4,5=14-13,5=0,5$

$\displaystyle\bf\\Otvet \ : \ \Big(15 \ ; \ -\frac{1}{3} \Big) \ , \ \Big(0,5 \ ; \ 4,5\Big)\\\\\\2)\\\\+\left \{ {{x^{2} + y^{2}+x+y=18 } \atop {x^{2} - y^{2} +x-y=6}} \right.\\ ------------\\2x^{2} +2x=24\\\\x^{2} +x-12=0\\\\Teorema \ Vieta \ :\\\\x_{1} + x_{2} =-1\\\\x_{1} \cdot x_{2} =-12\\\\x_{1} =-4 \ \ ; \ \ x_{2} =3\\\\1)\\\\x^{2} - y^{2} +x-y=6\\\\(-4)^{2} -y^{2} -4-y=6\\\\16-y^{2} -4-y-6=0\\\\y^{2} +y-6=0\\\\y_{1} =-3 \ \ ; \ \ y_{2} =2\\\\2)$

$\displaystyle\bf\\x^{2} - y^{2} +x-y=6\\\\3^{2} -y^{2} +3-y=6\\\\y^{2}+y-6 =0\\\\y_{3}=-3 \ \ ; \ \ y_{4} =2\\\\\\Otvet \ : \ (-4 \ ; \ -3) \ , \ (-4 \ ; \ 2) \ , \ (3\ ; \ -3) \ , \ (3 \ ; \ 2)$