1)5a+10/(2a^2+13a+18)
2a^2+13a+18=2(a+2)(a+4,5)
D=169-4*2*18=25
a1=-2, a2=-4,5
5a+10/(2a^2+13a+18)=5(a+2)/(2(a+2)(a+4,5))=5/(2a+9)
2)(y^2-5y-36)/(81-y^2)
y^2-5y-36=(y-9)(y+4)
D=25-4*1*(-36)=169
y1=9, y2=-4
(y^2-5y-36)/(81-y^2)=(y-9)(y+4)/((9-y)(9+y)=-(9-y)(y+4)/((9-y)(9+y))=-(y+4)/(9+y)
