1. The problem statement, all variables and given/known data At what points on the curve y = (x^2)/(2x+5) is the tangent line horizontal? 2. Relevant equations Quotient rule 3. The attempt at a solution I figured out the derivative which is 2x(2x+5) - 2x^2 ----------------- (2x+5)^2 I also know that for the equation of the tangent to be horizontal, it needs to have a slope of 0, so y' = 0 Therefore I tried to do 2x(2x+5) - 2x^2 = 0, and I got 2x^2 + 10x = 0 which means that x must be -5. However when I put it into the calculator, it doesn't agree with me, so I went wrong somewhere. Thanks in advance!