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