ok I have understand how to do it but i ave confuse when is removable and when is non-removable

here is the question:

Find any singularities or discontinuities in the following functions:

f(x)=(x+3)/(x^2-9)

(an:non-removable singularity at x=3, removable singularity at x=-3, put f(x)=-1/6)

f(x)=cosx/(x-π/2)

(an:removabe singularity at x=π/2, put f(π/2)=-1)