Chapter 5: Problem 5
When using a change of variables \(u=g(x)\) to evaluate the definite integral \(\int_{a}^{b} f(g(x)) g^{\prime}(x) d x,\) how are the limits of integration transformed?
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Chapter 5: Problem 5
When using a change of variables \(u=g(x)\) to evaluate the definite integral \(\int_{a}^{b} f(g(x)) g^{\prime}(x) d x,\) how are the limits of integration transformed?
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The population of a culture of bacteria has a growth rate given by \(p^{\prime}(t)=\frac{200}{(t+1)^{r}}\) bacteria per hour, for \(t \geq 0,\) where \(r>1\) is a real number. The increase in the population over the time interval \([0, t]\) is given by \(\int_{0}^{t} p^{\prime}(s) d s\). (Note that the growth rate decreases in time, reflecting competition for space and food.) a. Using the population model with \(r=2,\) what is the increase in the population over the time interval \(0 \leq t \leq 4 ?\) b. Using the population model with \(r=3,\) what is the increase in the population over the time interval \(0 \leq t \leq 6 ?\) c. Let \(\Delta P\) be the increase in the population over a fixed time interval \([0, T] .\) For fixed \(T,\) does \(\Delta P\) increase or decrease with the parameter \(r ?\) Explain. d. A lab technician measures an increase in the population of 350 bacteria over the 10 -hr period [0,10] . Estimate the value of \(r\) that best fits this data point. e. Looking ahead: Work with the population model using \(r=3\) in part (b) and find the increase in population over the time interval \([0, T],\) for any \(T>0 .\) If the culture is allowed to grow indefinitely \((T \rightarrow \infty),\) does the bacteria population increase without bound? Or does it approach a finite limit?
More than one way Occasionally, two different substitutions do the job. Use both of the given substitutions to evaluate the following integrals. $$\int \sec ^{3} \theta \tan \theta d \theta \quad(u=\cos \theta \text { and } u=\sec \theta)$$
Find the area of the following regions. The region bounded by the graph of \(f(x)=x \sin \left(x^{2}\right)\) and the \(x\) -axis between \(x=0\) and \(x=\sqrt{\pi}\).
More than one way Occasionally, two different substitutions do the job. Use both of the given substitutions to evaluate the following integrals. $$\int_{0}^{1} x \sqrt{x+a} d x ; a>0 \quad(u=\sqrt{x+a} \text { and } u=x+a)$$
Consider the function g. which is given in terms of a definite integral with a variable upper limit. a. Graph the integrand. b. Calculate \(g^{\prime}(x)\) c. Graph g, showing all your work and reasoning. $$g(x)=\int_{0}^{x} \sin ^{2} t d t$$
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