Computer Explorations

Use a CAS to perform the following steps in Exercises 55–62.

a. Plot the equation with the implicit plotter of a CAS. Check to see that the given point P satisfies the equation.

2y² + (xy)¹/³ = x² + 2, P(1,1)

Write the following logarithms in terms of the natural logarithm. Then use a calculator to find the value of the logarithm, rounding your result to four decimal places.

$the log base 6 of 60$

144

Changing bases Convert the following expressions to the indicated base.

$\ln ∣ x ∣$ using base 5

157

Convert the following expressions to the indicated base.

$a^{\frac{1}{\ln a}}$ using basa e, for $a is greater than 0$ and $a is not equal to 1$

149

97–100. Logistic growth Scientists often use the logistic growth function P(t) = P₀K / P₀+(K−P₀)e^−r₀t to model population growth, where P₀ is the initial population at time t=0, K is the carrying capacity, and r₀ is the base growth rate. The carrying capacity is a theoretical upper bound on the total population that the surrounding environment can support. The figure shows the sigmoid (S-shaped) curve associated with a typical logistic model. <IMAGE>

{Use of Tech} Gone fishing When a reservoir is created by a new dam, 50 fish are introduced into the reservoir, which has an estimated carrying capacity of 8000 fish. A logistic model of the fish population is P(t) = 400,000 / 50+7950e^−0.5t, where t is measured in years.

b. How long does it take for the population to reach 5000 fish? How long does it take for the population to reach 90% of the carrying capacity?

101

Which of the following best describes the function $E i (x)$ ?

Which of the following transformations results in a vertical stretch of the exponential decay function $f (x) = e^{- x}$ ?

What is the multiplicative rate of change of

Given the following table of values for an exponential function $f (x)$ :

$x$	$f (x)$
$0$	$3$
$1$	$6$
$2$	$12$
$3$	$24$

f (x)

rank

Which operation can be used to eliminate the natural logarithm ( $\ln$ ) from both sides of an equation such as $\ln (x) = 3$ ?