Chapter 3: Problem 64
Multiply as indicated. Write each product in standand form. $$(6-4 i)(6+4 i)$$
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Chapter 3: Problem 64
Multiply as indicated. Write each product in standand form. $$(6-4 i)(6+4 i)$$
These are the key concepts you need to understand to accurately answer the question.
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For each pair of numbers, find the values of \(a, b,\) and \(c\) for which the quadratic equation ax \(^{2}+b x+c=0\) has the given numbers as solutions. Answers may vary. (Hint: Use the zero-product property in reverses $$3 i,-3 i$$
Solve each problem. The table shows a person's heart rate during the first 4 minutes after exercise has stopped. $$\begin{array}{|l|c|c|c|} \hline \text { Time (min) } & 0 & 2 & 4 \\ \hline \text { Heart rate (bpm) } & 154 & 106 & 90 \\ \hline \end{array}$$ (a) Find a formula \(f(x)=a(x-h)^{2}+k\) that models the data, where \(x\) represents time and \(0 \leq x \leq 4 .\) Use \((4,90)\) as the vertex. (b) Evaluate \(f(1)\) and interpret the result. (c) Estimate the times when the heart rate was from 115 to 125 beats per minute.
Solve each problem. The table lists the average heating bill for a natural gas consumer in Indiana during various months of the year. $$\begin{array}{|c|c|} \hline \text { Month } & \text { Bill ( } \$ \text { ) } \\ \hline \text { Jan. } & 108 \\ \text { Mar. } & 68 \\ \text { May } & 18 \\ \text { July } & 12 \\ \text { Sept. } & 13 \\ \text { Nov. } & 54 \\\\\hline \end{array}$$ (a) Plot the data. Let \(x=1\) correspond to January, \(x=2\) to February, and so on. (b) Find a quadratic function \(f(x)=a(x-h)^{2}+k\) that models the data. Use \((7,12)\) as the vertex and \((1,108)\) as another point to determine \(a\) (c) Plot the data together with the graph of \(f\) in the same window. How well does \(f\) model the average heating bill over these months? (d) Use the quadratic regression feature of a graphing calculator to determine the quadratic function \(g\) that provides the best fit for the data. (e) Use the functions \(f\) and \(g\) to approximate the heating bill to the nearest dollar in the following months. (i) February (ii) June
Solve each equation for \(x\) and then for \(y .\) $$x^{2}+x y+y^{2}=0 \quad(x>0, y>0)$$
Solve each equation. For equations with real solutions, support your answers graphically. $$4 x^{2}-12 x=-11$$
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