Determine whether the following statements are true and give an explanation or counterexample.
The line x=−1 is a vertical asymptote of the function f(x) =x^2 − 7x + 6 / x^2 − 1.

The hyperbolic cosine function, denoted $\(\cosh\)\(\left\)(x\(\right\))$, is used to model the shape of a hanging cable (a telephone wire, for example). It is defined as $\(\cosh\)\(\left\)(x\(\right\))=\(\frac{e^{x}\)+e^{-x}}{2}$.

b. Evaluate $\cosh \left(0\right)$. Use symmetry and part (a) to sketch a plausible graph for $y=\cosh \left(x\right)$.

Complete the following steps for the given functions. 

b. Find the vertical asymptotes of $f$ (if any).

$f\left(x\right)=\frac{x^2-3}{x+6}$

Assume you invest \$250 at the end of each year for 10 years at an annual interest rate of $r$. The amount of money in your account after 10 years is given by $A\left(r\right)=\frac{250({(1+r)}^{10}-1)}{r}$. Assume your goal is to have \$3500 in your account after 10 years.

b. Use a calculator to estimate the interest rate required to reach your financial goal.

Let $g\(\left\)(x\(\right\))=\(\begin{cases}\)x^2+x & \(\text{if }\)x<1\\ a & \(\text{if }\)x=1\\ 3x+5 & \(\text{if }\)x>1\(\end{cases}\)$

b. Determine the value of $a$ for which $g$ is continuous from the right at $1$. 

The graph of f in the figure has vertical asymptotes at x=1 and x=2. Analyze the following limits. <IMAGE>

lim x→1^+ f(x)

Use analytic methods to find the value of lim x→π/4 cos 2x / cos x − sin x.