at what point is the tangent to f(x)=x^2+4x-1 horizontal?
That would be when the derivative, df/dx = 2x + 4, equals zero.
df/dx at any point of a curve f(x) is the slope of the tangent line.
That would be when the derivative, df/dx = 2x + 4, equals zero.
df/dx at any point of a curve f(x) is the slope of the tangent line.