Question

Помогите, пожалуйста решить

Answer 1

$1); left { {{xy=-12} atop {x^2+y^2=25}} right. ; left { {{2xy=-24} atop {x^2+2xy+y^2=-24+25}} right. ; left { {{xy=-12} atop {(x+y)^2=1}} right. ; left { {{xy=-12} atop {x+y=pm 1}} right. \\a); ; left { {{xy=-12} atop {x+y=1}} right. ; left { {{x=-frac{12}{y}} atop {-frac{12}{y}+y=1}} right. ; left { {{x=frac{-12}{y}} atop {y^2-y-12=0,; yne 0}} right. ; y_{1,2}=-3,4\\x_{1,2}=4,-3$

$b); left { {{xy=-12} atop {-frac{12}{y}+y=-1}} right. ; left { {{x=frac{-12}{y}} atop {frac{-12}{y}+y=-1}} right. ; left { {{x=frac{-12}{y}} atop {y^2+y-12=0}} right. ; ;; y_{1,2}=3,-4\\x_{1,2}=-4,3\\Otvet:; (-3,4),(4,-3),(3,-4),(-4,3).$

$3); left { {frac{x+3y}{ 2}=frac{x-2y}{3}+31, |cdot 6atop {x+y=frac{3}{4}(x-y)+27, |cdot 4}} right. ; left { {{3(x+3y)=2(x-2y)+186} atop {4(x+y)=3(x-y)+108}} right. ; left { {{x+13y=186} atop {x+7y=108}} right. \\ left { {{13y-7y=186-108} atop {x+7y=108}} right. ; left { {{6y=78} atop {x=108-7y}} right. ; left { {{y=13} atop {x=17}} right. \\Otvet:; (17,13).$

$2); left { {{3(3x-y)+frac{2}{5}(x-2y)=17, |cdot 5} atop {5x+y=3}} right. ; left { {{15(3x-y)+2(x-2y)=85} atop {y=3-5x}} right. ; left { {{47x-19y=85} atop {y=3-5x}} right. \\ left { {{47x-19(3-5x)=85} atop {y=3-5x}} right. ; left { {{142x=142} atop {y=3-5x}} right. ; left { {{x=1} atop {y=-2}} right. \\Otvet:; (1,-2)$

Answer 2

Спасибо!