Let be the rational function given by

MATHEMATICS · Multi-part · A Level · Mathematics · Differentiation · Differentiation

Problem

Let gg be the rational function given by g(x)=x2+1x−1g(x)=\dfrac{x^{2}+1}{x-1}. The domain of gg excludes x=1x=1. Consider gg on the interval [−2,4][-2,4], noting that x=1x=1 creates a break in the domain. (a) Compute g′(x)g'(x) and simplify your result. (b) Identify all xx–values in (−2,4)(-2,4) at which g′(x)=0g'(x)=0 or is undefined. Combine these with the point of discontinuity x=1x=1 to create the critical set for gg on the given interval. (c) Construct a sign chart for g′(x)g'(x) on [−2,4][-2,4], carefully addressing the discontinuity at x=1x=1. (d) Using the sign chart, determine the intervals on which gg is increasing and the intervals on which it is decreasing. Then classify every critical point from part (b) as a local maximum, local minimum, or neither. Provide justification for each classification. (e) Evaluate gg at all critical points from part (b) that lie in the domain as well as at the endpoints x=−2x=-2 and x=4x=4. Discuss whether an absolute maximum or absolute minimum of gg exists on [−2,4][-2,4], and support your conclusion.

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