Question 639304
How do I factor 25y^2 - 10y + 1? 

I thought it was a perfect square trinomial, but that doesn't make sense because of the + 1. And I tried factoring it out by taking 5y out, but that doesn't match the answer in the back of my book. I don't know how they got that answer. The answer to the question is (5y - 1)^2.
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What's wrong with that?
-1*-1 = +1