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## Homework Statement

I'm trying to go through something shown in a lecture and the part I'm stuck on is shown here.

[tex]\frac{\partial}{\partial t}\int^t_0 \mbox{du }e^{i \omega(t-u)}\hat{b}(u)=\hat{b}(t)[/tex]

[tex]\hat{b}(u)[/tex] is an annihilation operator

## The Attempt at a Solution

Can someone explain how this step is made? Obviously a delta function has to come in somewhere but I don't know how to do that with a derivative (only another integral).