Created
June 3, 2010 02:35
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\documentclass{article} | |
\usepackage{graphicx} | |
\begin{document} | |
\noindent\textbf{5:} | |
{\center \[ f(x) = \frac{(x^2 - 8x + 7)}{(x - 6)} \]} | |
\includegraphics[width=5in,height=3.1in]{question5.pdf} | |
\noindent\emph{The Asymptotes:} | |
Since the denominator of \( f(x) \) is 0 at \( x = 6\), there is a vertical asymptote at that point. | |
Because the degree of the numerator is a degree higher than the denominator, we have a slant asymptote. To find the equation of the slant asymptote, we must take the limit of the function. | |
\[ \lim_{x\to\infty} f(x) = (x^2 - 8x + 7) \div (x - 6) = x - 2 \] | |
% This is where I will hand-write the synthetic division. | |
\newpage | |
\noindent\emph{The Points:} | |
Next, simply pick a few points and plot them on the graph, then connect the points with a curve. | |
\begin{center} | |
\begin{tabular}{r|r} | |
$x$&$y$\\ | |
\hline | |
0&\(\frac{-7}{6}\)\\ | |
1&0\\ | |
5&8\\ | |
7&0\\ | |
6.5&-5.5\\ | |
\end{tabular} | |
\end{center} | |
\noindent\textbf{14:} | |
\emph{D} is the correct answer because that function has a range of $(\infty , 0)$. | |
\noindent \textbf{20:} | |
This requires the change of base formula. | |
\[ \frac{\log_{n} 0.0123}{\log_{n} 4} = -3.1726 \] | |
Where $n$ is any base. | |
\noindent \textbf{29:} | |
\[\log_2(x+5) - \log_2(x-1) = 2\log_22\] | |
The first thing to do in this case is to condense both sides of the equation. Recall that: | |
\[\log_n(x) - \log_n(y) = \log_n(\frac{x}{y}) \] | |
and that: | |
\[a \log_n(x) = \log_n(x^a)\] | |
The rest is straightforward algebra. | |
\begin{eqnarray*} | |
\log_2(x+5) - \log_2(x-1) &=& 2\log_22 \\ | |
\log_2(\frac{x+5}{x-1}) &=& \log_22^2 \\ | |
\frac{x+5}{x-1} &=& 4 \\ | |
x+5 &=& 4(x-1) \\ | |
x+5 &=& 4x - 4 \\ | |
9 &=& 3x \\ | |
3 &=& x\\ | |
\end{eqnarray*} | |
\newpage | |
\noindent \textbf{35:} | |
\[ f(x) = 29 + 49 log(x+1) \] | |
\emph{a:} This is simply a matter of plugging in 9 for $x$. | |
\[ f(9) = 29 + 49 log(9+1) = 78 \] | |
\emph{b:} Here we know that $f(x) = 90$. So: | |
\begin{eqnarray*} | |
90 &=& 29 + 49 log( x + 1 )\\ | |
\frac{61}{49} &=& log( x + 1 )\\ | |
10^{\frac{61}{49}} &=& x + 1\\ | |
10^{\frac{61}{49}} - 1 &=& x\\ | |
16.58 &\approx& x | |
\end{eqnarray*} | |
\noindent \textbf{59:} | |
The intercept of an axis occurs when all other axis are equal to 0. therefore, to find the $x$-intercept, the $y$- and $z$- axis must be equal to 0. It therefore becomes extremely simple to solve for this sort of thing. | |
\begin{center} | |
\begin{tabular}{r|r|r} | |
Intercept&Formula&Solution\\ | |
\hline | |
$x$& \(5x = 20\) &\(x = 4\) \\ | |
$y$& \(2y = 20\) &\(y = 10\)\\ | |
$z$& \(-4z = 20\)&\(z = -5\)\\ | |
\end{tabular} | |
\end{center} | |
\noindent \textbf{65:} | |
Since we know that $x = r cos(\theta)$ and that $y = r sin(\theta)$, this is a simple case of plugging in $-4$ for $r$ and $\frac{-7\pi}{4}$ for $\theta$. | |
\[(-4cos(\frac{-7\pi}{4}), -4sin(\frac{-7\pi}{4})) = (-2\sqrt{2}, -2\sqrt{2})\] | |
\noindent \textbf{74:} | |
Because this series does not have a common difference, it is a geometric function. The standard form for a geometric series that increases without bound is simply: | |
\[\sum_{n =1}^{\infty} a_0(r^{n-1})\] | |
It starts at 8 and continues without bound. Because it doubles each time, we know that $r = 2$. We also know that $a_0 = 8$. Therefore, the summation notation is: | |
\[ \sum_{n=1}^{\infty} 8(2^{n-1}) \] | |
\end{document} |
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