IB Calculus Problem 22

Consider \(f(x) = x\ln(4 - x^2)\), with \(-2 < x < 2\).

Part of the graph of \(f\) is shown below.

image essential to understanding the question

Let \(P\) and \(Q\) be the points on the curve of \(f\) where the tangent to the graph of \(f\) is parallel to the x-axis.

    1. Find the x-coordinates of \(P\) and \(Q\).

    2. Consider \(f(x) = k\).

      State all values of \(k\) for which there are exactly two solutions.

Let \(g(x) = x^3\ln(4 - x^2)\), with \(-2 < x < 2\).

  1. Show that \(g^\prime(x)=\frac{-2x^4}{4 - x^2} + 3x^2\ln(4 - x^2)\).

  2. Sketch the graph of \(g^\prime\).

  3. Consider \(g^\prime(x) = w\).

    State all values of \(w\) for which there are exactly two solutions.

Published by Annie Bernatchez in «calculus». Key Words: IB, question