1
(2x-3)/(x+5)=4
x≠-5
2x-3=4x+20
4x-2x=-3-20
2x=-23
x=-23:2
x=-11,5
2
{x-y=12⇒x=y+12
{3x/5-y=y(y-1)
0,6*(12+y)-y=y²-y
y²-0,6y-7,2
y1+y2=0,6 U y1*y2=-7,2
y1=3⇒x1=3+12=15
y2=-2,4⇒x2=-2,4+12=9,6
(15;3);(9,6;-2,4)
3
{x+y=2
{(x²-2-y²)/2=1⇒x²-y²=4⇒(x-y)(x+y)=4⇒2(x-y)=4⇒x-y=2
прибавим
2x=4
x=2
2+y=2
y=0
(2;0)
4
{5/(x-4)=2/(y-1)⇒5y-5=2x-8⇒-2x+5y=-3/*(-2)⇒4x-10y=6
{3/(x+2)=4/(y+1)⇒3y+3=4x+8⇒-4x+3y=5
прибавим
-7y=11
y=-11/7
-2x-55/7=-3
2x=3-55/7
2x=-34/7
x=-17/7
(-17/7;-11/7)