Chapter 5

A Graphical Approach to College Algebra · 468 exercises

Problem 85

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$\frac{1}{2} e^{2 x}+e^{x}=1$$

8 step solution

Problem 86

Assume that \(f(x)=a^{x},\) where \(a>1\) If the point \((p, q)\) is on the graph of \(f,\) then the point ______ is on the graph of \(f^{-1}\)

3 step solution

Problem 86

Use the properties of logarithms to rewrite each expression as a single logarithm with coefficient 1. Assume that all variables represent positive real numbers. $$\frac{1}{2} \log x-\frac{1}{3} \log y-2 \log z$$

3 step solution

Problem 86

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$\frac{1}{4} e^{2 x}+2 e^{x}=3$$

7 step solution

Problem 87

Use the properties of logarithms to rewrite each expression as a single logarithm with coefficient 1. Assume that all variables represent positive real numbers. $$\ln (a+b)+\ln a-\frac{1}{2} \ln 4$$

4 step solution

Problem 87

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$3^{2 x}+35=12\left(3^{x}\right)$$

7 step solution

Problem 88

Use the properties of logarithms to rewrite each expression as a single logarithm with coefficient 1. Assume that all variables represent positive real numbers. $$\frac{4}{3} \ln m-\frac{2}{3} \ln 8 n-\ln m^{3} n^{2}$$

5 step solution

Problem 88

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$5^{2 x}+3\left(5^{x}\right)=28$$

6 step solution

Problem 89

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{5} 10$$

4 step solution

Problem 89

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$\left(\log _{2} x\right)^{2}+\log _{2} x=2$$

7 step solution

Problem 90

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{9} 12$$

5 step solution

Problem 90

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$(\log x)^{2}-6 \log x=7$$

6 step solution

Problem 91

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{15} 5$$

5 step solution

Problem 91

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$(\ln x)^{2}+16=10 \ln x$$

6 step solution

Problem 92

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{1 / 2} 3$$

4 step solution

Problem 92

$$\text { The given equations are quadratic in form. Solve each and give exact solutions.}$$ $$2(\ln x)^{2}+9 \ln x=5$$

6 step solution

Problem 93

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{100} 83$$

5 step solution

Problem 93

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=-2 e^{x}+5$$

6 step solution

Problem 94

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{200} 175$$

4 step solution

Problem 94

Decide whether the pair of functions \(f\) and \(g\) are inverses. Assume axes have equal scales. CAN'T COPY THE GRAPH $$f(x)=-\frac{3}{11} x, \quad g(x)=-\frac{11}{3} x$$

4 step solution

Problem 94

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=-3 e^{x}+7$$

2 step solution

Problem 95

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{29} 7.5$$

5 step solution

Problem 95

Decide whether the pair of functions \(f\) and \(g\) are inverses. Assume axes have equal scales. CAN'T COPY THE GRAPH $$f(x)=2 x+4, \quad g(x)=\frac{1}{2} x-2$$

3 step solution

Problem 95

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=2\left(3^{x}\right)-18$$

3 step solution

Problem 96

Use the change-of-base rule to find an approximation for each logarithm. $$\log _{5.8} 12.7$$

6 step solution

Problem 96

Decide whether the pair of functions \(f\) and \(g\) are inverses. Assume axes have equal scales. CAN'T COPY THE GRAPH $$f(x)=5 x-5, \quad g(x)=\frac{1}{5} x+5$$

4 step solution

Problem 96

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=4^{x-2}-2$$

4 step solution

Problem 97

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=3^{2 x}-9^{x+1}$$

5 step solution

Problem 98

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=2^{3 x}-8^{x-3}$$

6 step solution

Problem 99

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=8-4 \log _{5} x$$

7 step solution

Problem 100

For individual or group investigation (Exercises \(97-102\) ) Work Exercises \(97-102\) in order. Solve \(0=-3^{x}+7\) for \(x,\) expressing \(x\) in terms of base 3 logarithm.

4 step solution

Problem 100

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=9 \log _{3}(3 x)-18$$

6 step solution

Problem 101

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=\ln (x+2)$$

4 step solution

Problem 102

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=\ln (x-1)-\ln (x+1)$$

4 step solution

Problem 102

Graph the inverse of each one-to-one function. CAN'T COPY THE GRAPH

6 step solution

Problem 103

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=7-5 \log x$$

4 step solution

Problem 103

The equations are identities because they are true for all real numbers. Use properties of logarithms to simplify the expression on the left side of the equation so that it equals the expression on the right side, where \(x\) is any real number. $$\ln |x+\sqrt{x^{2}+3}|+\ln |x-\sqrt{x^{2}+3}|=\ln 3$$

5 step solution

Problem 104

For the given \(f(x)\), solve the equation \(f(x)=0\) analytically and then use a graph of \(y=f(x)\) to solve the inequalities \(f(x)<0\) and \(f(x) \geq 0\) $$f(x)=3-2 \log _{4}(x-5)$$

4 step solution

Problem 104

The equations are identities because they are true for all real numbers. Use properties of logarithms to simplify the expression on the left side of the equation so that it equals the expression on the right side, where \(x\) is any real number. $$\ln \left|x^{2}-\sqrt{x^{4}+1}\right|+\ln \left|x^{2}+\sqrt{x^{4}+1}\right|=0$$

5 step solution

Problem 105

Suppose \(f(x)\) is the number of cars that can be built for \(x\) dollars. What does \(f^{-1}(1000)\) represent?

3 step solution

Problem 105

In general, it is not possible to find exact solutions analytically for equations that involve exponential or logarithmic functions together with polynomial, radical, and rational functions. Solve each equation= using a graphical method, and express solutions to the nearest thousandth if an approximation is appropriate. $$x^{2}=2^{x}$$

4 step solution

Problem 105

The equations are identities because they are true for all real numbers. Use properties of logarithms to simplify the expression on the left side of the equation so that it equals the expression on the right side, where \(x\) is any real number. $$\frac{1}{3} \ln \left(\frac{x^{2}+1}{5}\right)-\frac{1}{3} \ln \left(\frac{x^{2}+4}{5}\right)=\ln \sqrt[3]{\frac{x^{2}+1}{x^{2}+4}}$$

4 step solution

Problem 106

Suppose \(f(r)\) is the volume (in cubic inches) of a sphere of radius \(r\) inches. What does \(f^{-1}(5)\) represent?

4 step solution

Problem 106

In general, it is not possible to find exact solutions analytically for equations that involve exponential or logarithmic functions together with polynomial, radical, and rational functions. Solve each equation= using a graphical method, and express solutions to the nearest thousandth if an approximation is appropriate. $$x^{2}-4=e^{x-4}+4$$

5 step solution

Problem 106

The equations are identities because they are true for all real numbers. Use properties of logarithms to simplify the expression on the left side of the equation so that it equals the expression on the right side, where \(x\) is any real number. $$\frac{1}{2} \ln \left(\frac{x^{2}}{7}\right)-\frac{1}{2} \ln \left(\frac{x^{4}+x^{2}}{7}\right)=\ln \sqrt{\frac{1}{x^{2}+1}}$$

5 step solution

Problem 107

If a line has nonzero slope \(a\), what is the slope of its reflection across the line \(y=x ?\)

5 step solution

Problem 107

In general, it is not possible to find exact solutions analytically for equations that involve exponential or logarithmic functions together with polynomial, radical, and rational functions. Solve each equation= using a graphical method, and express solutions to the nearest thousandth if an approximation is appropriate. $$\log x=x^{2}-8 x+14$$

5 step solution

Problem 107

Suppose a sample of a small community shows two species with 50 individuals each. Find the index of diversity \(H=-\left(P_{1} \log _{2} P_{1}+P_{2} \log _{2} P_{2}+\cdots+P_{n} \log _{2} P_{n}\right)\).

5 step solution

Problem 108

$$\text { Find } f^{-1}(f(2)), \text { where } f(2)=3$$

4 step solution

Problem 108

In general, it is not possible to find exact solutions analytically for equations that involve exponential or logarithmic functions together with polynomial, radical, and rational functions. Solve each equation= using a graphical method, and express solutions to the nearest thousandth if an approximation is appropriate. $$\ln x=-\sqrt[3]{x+3}$$

5 step solution

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