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**1. The problem statement, all variables and given/known data**

Verify that y1 = (e^x) * (cos x) solves the linear, homogeneous, 2nd order differential equation y'' - 2y' + 2y = 0

**2. Relevant equations**

**3. The attempt at a solution**

So I used the product rule but just kept going in circles with the cos x. I remember there's a way to do this so you don't go in circles, but I forgot! I'd appreciate any help.