For what values of x does the curve y^2-x^3-15x^2=8 have horizontal tangent lines? Answer: x=0 and x=-10 2/9/2014 | Sun from Los Angeles, CA | 1 Answer | 0 Votes Mark favorite Subscribe Comment
Horizontal tangent means slope is zero; so 1st derivative is zero. 2yy' - 3x^2 - 30x = 0 y' = 0 so 3x^2 + 30x = 0 x(x + 10) = 0 x = 0, -10 2/9/2014 | Steve S. Comment Comments Thanks. 2/9/2014 | Sun from Los Angeles, CA Comment
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