Question

розв'яжіть систему рівнянь
5x+3xy=-4
y-3xy=-7​

Answer 1

$+\left \{ {{5x+3xy=-4} \atop {y-3xy=-7}} \right.\\ -------\\5x+y=-11\\y=-5x-11\\5x+3x*(-5x-11)=-4\\5x-15x^{2}-33x+4=0\\15x^{2}+28x-4=0\\ D=28^{2}-4*15*(-4)=784+240=1024=32^{2}\\\\x_{1}=\frac{-28-32}{30}=-2\\\\x_{2} =\frac{-28+32}{30}=\frac{2}{15}\\\\y_{1} =-5*(-2)-11=-1\\\\y_{2}=-5*\frac{2}{15}-11=-\frac{2}{3}-11=-11\frac{2}{3}\\\\Otvet:(-2;-1),(\frac{2}{15};-11\frac{2}{3})$