Question

СРОЧНО!!!
ПОМОГИТЕ ПОЖАЛУЙСТА

Answer 1

$1)+left { {{2x+5xy=14} atop {y-5xy=-9}} right.\--------\2x+y=5\\y=5-2x\\left { {{2x+5x*(5-2x)=14} atop {y=5-2x}} right.\\left { {{2x+25x-10x^{2}-14=0 } atop {y=5-2x}} right. \\left { {{10x^{2}-27x+14=0 } atop {y=5-2x}} right.\\10x^{2}-27x+14=0\\D=(-27)^{2}-4*10*14=729-560=169=13^{2}\\x_{1}=frac{27-13}{20}=0,7\\x_{2}=frac{27+13}{20}=2\\y_{1}= 5-2*0,7=3,6\\y_{2}=5-2*2=1\\Otvet:boxed{(0,7;3,6),(2;1)}$

2) Сделаем замену :

$xy=m,frac{x}{y}=n\\left { {{m-n=6}|*2 atop {3m+2n=28}} right.\\+left { {{2m-2n=12} atop {3m+2n=28}} right.\ -------\5m=40\\m=8\\n=m-6=8-6=2\\left { {{xy=8} atop {frac{x}{y}=2 }} right. \\left { {{x=2y} atop {2y*y=8}} right.\\left { {{x=2y} atop {y^{2}=4 }} right.$

$1)left { {{x=2y} atop {y_{1}=-2 }} right.\\left { {{x_{1}=2*(-2)=-4 } atop {y_{1}=-2}} right.\\2)left { {{x=2y} atop {y_{2}=2}} right.\\left { {{x_{2}=2*2=4 } atop {y_{2}=2 }} right. \\Otvet:boxed{(-4;-2),(4;2)}$