Question

Решите систему уравнений!!!!
Срочно

Answer 1

$left { {{ log_{2} x+ log_{2} y=2} atop {x-4y=15}} right.$
$left { {{ log_{2} x*y=2log_{2}2} atop {x=15+4y}} right.$
$left { {{ xy=4} atop {x=15+4y}} right.$
$left { {{ (15+4y)y=4} atop {x=15+4y}} right.$
$left { {{ 15y+4y^2-4=0} atop {x=15+4y}} right.$
$4y^2+15y-4=0$
$D=225-4*4*(-4)=225+64=289$
$y_{1} = frac{-15+17}{8} = frac{1}{4}$
$y_{2} = frac{-15-17}{8} = -4$


$left { {{y= frac{1}{4} } atop {x=15+4y}} right.$
$left { {{y= frac{1}{4} } atop {x=15+4* frac{1}{4} }} right.$
$left { {{y= frac{1}{4} } atop {x=15+1}} right.$
$left { {{y= frac{1}{4} } atop {x=16}} right.$

$left { {{y= -4} atop {x=15+4y}} right.$
$left { {{y= -4} atop {x=15+4*(-4)}} right.$
$left { {{y= -4} atop {x=15-16}} right.$
$left { {{y= -4} atop {x=-1}} right.$
ответ: (16;1/4);(-4;1)