Question 315999
A student factored 5y^3 + 55y^2 +90y by first factoring out 5y to get 
5y(y^2 + 11y + 18).  He wrote the answer (y + 2)(y + 9) as the factored answer. Why is this answer wrong?
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If you multiply (y + 2)(y + 9), you don't get 5y^3 + 55y^2 +90y, so it's wrong.