Interpreting the Sign of the First Derivative (Increasing and Decreasing Functions)

Key Questions

  • Answer:

    It will be increasing when the first derivative is positive.

    Explanation:

    Take the example of the function f(x) = e^(x^2 - 1).

    The first derivative is given by f'(x) = 2xe^(x^2 - 1) (chain rule). We see that the derivative will go from increasing to decreasing or vice versa when f'(x) = 0, or when x= 0.

    Whenever you have a positive value of x, the derivative will be positive, therefore the function will be increasing on {x|x> 0, x in RR}.

    The graph confirms

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    Hopefully this helps!

  • Answer:

    If x_0 < x_1 then f(x_0) < f(x_1)

    Explanation:

    The meaning is that you have a function with positive slope in every point of Dom.

    Starting from a x_0 and move to right, the graph of function is moving up at the same time

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