решите уравнение х^2/x+3=2x+3/x+3
2x/x+6 - 144/x^2-36=1

1) x^2/(x+3) -(2x+3)/(x+3)=0
(x^2-2x-3)/(x+3)=0
x^2-2x-3=0
D=4+12=16=4^2
x1=(2+4)/2=6
x2=(2-4)/2= -1

2) 2x(x-6)-144)/(x-6)(x+6)=1
2x^2-12x-144=x^2-36
2x^2-12x-144-x^2+36=0
x^2-12x-108=0
D=144+432=576=24^2
x1=(12+24)/2=18
x2=(12-24)/2= -6