Finding an integrated rate equation

[bluepen]

Hey there,

I can't for the life of me see how you start separating and integrating from this:

d[I]/dt + kb[I] = ka[A]0e-kat

A -> I -> P is the reaction

Is it really necessary to use the Method of Integrating Factors to get an expression for [I]?

I'm just looking for a gentle prod in the right direction!

Thanks,
Lydia