Chapter 8: Problem 13
Find all complex-number solutions. $$ 9 x^{2}-49=0 $$
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Chapter 8: Problem 13
Find all complex-number solutions. $$ 9 x^{2}-49=0 $$
These are the key concepts you need to understand to accurately answer the question.
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Solve each formula for the indicated letter. Assume that all variables represent positive numbers. \(A=2 \pi r^{2}+2 \pi r h,\) for \(r\) (Surface area of a right cylindrical solid)
Hydrology. The following drawing shows the cross section of a river. Typically rivers are deepest in the middle, with the depth decreasing to 0 at the edges. A hydrologist measures the depths \(D,\) in feet, of a river at distances \(x,\) in feet, from one bank. The results are listed in the following table. $$ \begin{array}{|c|c|} \hline \text { Distance x, } & {\text { Depth } D \text { of }} \\ {\text { from the Left }} & {\text { the River }} \\ {\text { Bank (in feet) }} & {\text { (in feet) }} \\ \hline 0 & {0} \\ {15} & {10.2} \\ {25} & {17} \\ {50} & {20} \\ {90} & {7.2} \\ {100} & {0} \\ \hline \end{array} $$ a) Use regression to find a quadratic function that fits the data. b) Use the function to estimate the depth of the river 70 ft from the left bank.
A well and a spring are filling a swimming pool. Together, they can fill the pool in 3 hr. The well, working alone, can fill the pool in 8 hr less time than it would take the spring. How long would the spring take, working alone, to fill the pool?
Solve. $$ \frac{1}{2}(x-7)=\frac{1}{3} x+4 $$
Solve each formula for the indicated letter. Assume that all variables represent positive numbers. \(F=\frac{G m_{1} m_{2}}{r^{2}},\) for \(r\) (Law of gravity)
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