498.
3) (y² +1)/(y² +2y) -2/(y+2) = (y² +1)/ y(y +2) - 2/(y+2) =(y² +1 -2y) / y(y +2) =
(y -1)² / y(y +2) ;
* * *(y-1)/y : (y -1) / y(y +2) = (y-1)/y * y(y +2) / (y -1)² =(y+2)/ (y-1) . * * *
499.
3)(c+d)/c -2c / (c-d) = (d+c)/c +2c / (d - c) =( (d+c)(d-c) +2c²) /c (d - c) =
(d² -c²+2c²) /c(c-d) = (d² +c²) /c(d-c) ;
* * *(d² +c²) / c(d- c) *(d-c) /(c² +d²) = (d² +c²)*(d-c) / c (d-c) *(d² +c²) =1/c * * *