Let
(x+1)2(x+4)x+5=(x+1)A+(x+1)2B+(x+4)C⇒x+5=A(x+1)(x+2)+B(x+2)+c(x+1)2⇒x+5=x2(A+C)+x(3A+B+2C)+2A+2B+C.Oncomparingthecoefficientsoflikepowerofx
,wegetA+C3A+B+2C=0,=1 and 2A+2B+C=5OnsubstitutingA=-C
inlasttwoequations,wegetB−C2B−C=1=5and2B−C=5OnsubtractingEqs.(ii)and(iii),wegetB=4⇒C=3[fromEq.(ii)]andhenceA=-3
Now,\frac{(x+5)}{(x+1)^2(x+2)}=\frac{-3}{(x+1)}+\frac{4}{(x+1)^2}+\frac{3}{(x+2)}
Ondifferentiatingbothsidesw.r.tx
,weget.\frac{d}{d x}\left(\frac{(x+5)}{(x+1)^2(x+4)}\right)=\frac{3}{(x+1)^2}-\frac{8}{(x+1)^3}-\frac{3}{(x+2)^2}