Question

explain this partial fraction​

Answer 1

f(z)=z^2-1/(z+2)(z+3) =1+A/(z+2)+B/(z+3)

(the cross multiplication between the above elements)

= 1+A(z+3)+B(z+2)/(z+2)(z+3)

z^2-1=(z+2)(z+3 )+A(z+3)+B(z+2)

Compare both sides elements

Az=0; 3A=-1 Bz=0; 2B=-1

A=-4 B=-3

f(z) = z^2-1/(z+2)(z+3)=1-4/(z+2)-3/(z+3)