at what point do the graph of the function f(x)=(x^2)+4x-1 have a horizontal tangent?
2 answers
That is a parabola. It is horizontal at the vertex.
Of course you could do it the sophisticated way, where the derivative is zero
f' = 2 x + 4
= 0 when x = -2
then
y = -5
f' = 2 x + 4
= 0 when x = -2
then
y = -5