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Integration by Substitution. Antidifferentiation of a Composite Function. Antidifferentiation of a Composite Function.
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Integration by Substitution Antidifferentiation of a Composite Function
Antidifferentiation of a Composite Function • Let g be a function whose range is an interval I, and let f be a function that is continuous on I. If g is differentiable on its domain and F is an antiderivative of f on I, then
Exploration • Recognizing Patterns. Discover the rule using the exploration
Recognizing the f’(g(x)) g’(x) Pattern • Evaluate
Recognizing the f’(g(x)) g’(x) Pattern • Evaluate
Multiplying and Dividing by a Constant • Evaluate
Evaluating an Integral We presently have no division rule for integrals. As a matter of fact there will never be a rule that involves division. Suggestions?
Change of Variables • We are allowed to multiply any integral by a constant, but we can never multiply by a variable. What can we do if there is an extra variable in the given equation?
Integration by Substitution • Evaluate • There is an extra x in this integrand. In order to solve this equation, we will let • u = 2x – 1.
Integration by Substitution • Now solve this equation for x
Integration by Substitution • This is a correct answer, but it can be simplified a little further. If the problem is not a multiple choice question on the test or quiz, this answer is completed. If it is a multiple choice question, it will be given as
Integrating Trig Functions • Remember that you need the derivative of the trig function and the function.
Guidelines for Making a Change of Variable • Choose a substitution u = g(x). Usually, it is best to choose the inner part of a composite function, such as a quantity raised to a power. • Compute du = g’(x) dx. • Rewrite the integral in terms of the variable u. • Evaluate the resulting integral in terms of u. • Replace u by g(x) to obtain an antiderivative in terms of x. • Check your answer by differentiating.
General Power Rule for Integration • If g is a differentiable function of x, then
Integration of Even and Odd Functions • Let f be integrable on the closed interval, [a, –a ], • 1. If f is an even function, then • 2. If f is an odd function, then