Question Help

Given the function f(x)=x^2-8x+13f(x)=x, determine the average rate of change of the function over the interval −1≤x≤6.

Ann [662]

Given:

Consider the given function is:

$f(x)=x^2-8x+13$

To find:

The average rate of change of the function over the interval $-1\leq x\leq 6$ .

Solution:

The average rate of change of the function f(x) over the interval [a,b] is:

$m=\dfrac{f(x_2)-f(x_1)}{x_2-x_1}$

We have,

$f(x)=x^2-8x+13$

At $x=-1$ ,

$f(-1)=(-1)^2-8(-1)+13$

$f(-1)=1+8+13$

$f(-1)=22$

At $x=6$ ,

$f(6)=(6)^2-8(6)+13$

$f(6)=36-48+13$

$f(6)=1$

Now, the average rate of change of the function f(x) over the interval $-1\leq x\leq 6$ is:

$m=\dfrac{f(6)-f(-1)}{6-(-1)}$

$m=\dfrac{1-22}{7}$

$m=\dfrac{-21}{7}$

$m=-3$

Therefore, the average rate of change of the function f(x) over the interval $-1\leq x\leq 6$ is -3.

6 0

3 years ago

The area of a circle is 113.04 in.^2. What is the radius of the circle?

Lelechka [254]

$\bf \textit{area of a circle}\\\\
A=\pi r^2\qquad 
\begin{cases}
r=radius\\
------\\
A=113.04
\end{cases}\implies 113.04=\pi r^2
\\\\\\
\cfrac{113.04}{\pi }=r^2\implies \sqrt{\cfrac{113.04}{\pi }}=r$

5 0

3 years ago

Michael bought vegetables that weights 4 1/8 pounds. How many ounces does the vegetables weigh?

Naddik [55]

There are 16 ounces in a pound. So in 4 1/8 pounds, there would be 66 ounces.

8 0

3 years ago

Read 2 more answers

How to write 0.038383838 in bar notation?

Annette [7]

Answer:

I think it would be 0.038

with a line over the 38

Step-by-step explanation:

8 0

3 years ago

You are a lifeguard and spot a drowning child 60 meters along the shore and 40 meters from the shore to the child. You run along

sukhopar [10]

Answer:

The lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

Step-by-step explanation:

This is a problem of optimization.

We have to minimize the time it takes for the lifeguard to reach the child.

The time can be calculated by dividing the distance by the speed for each section.

The distance in the shore and in the water depends on when the lifeguard gets in the water. We use the variable x to model this, as seen in the picture attached.

Then, the distance in the shore is d_b=x and the distance swimming can be calculated using the Pithagorean theorem:

$d_s^2=(60-x)^2+40^2=60^2-120x+x^2+40^2=x^2-120x+5200\\\\d_s=\sqrt{x^2-120x+5200}$

Then, the time (speed divided by distance) is:

$t=d_b/v_b+d_s/v_s\\\\t=x/4+\sqrt{x^2-120x+5200}/1.1$

To optimize this function we have to derive and equal to zero:

$\dfrac{dt}{dx}=\dfrac{1}{4}+\dfrac{1}{1.1}(\dfrac{1}{2})\dfrac{2x-120}{\sqrt{x^2-120x+5200}} \\\\\\\dfrac{dt}{dx}=\dfrac{1}{4} +\dfrac{1}{1.1} \dfrac{x-60}{\sqrt{x^2-120x+5200}} =0\\\\\\ \dfrac{x-60}{\sqrt{x^2-120x+5200}} =\dfrac{1.1}{4}=\dfrac{2}{7}\\\\\\ x-60=\dfrac{2}{7}\sqrt{x^2-120x+5200}\\\\\\(x-60)^2=\dfrac{2^2}{7^2}(x^2-120x+5200)\\\\\\(x-60)^2=\dfrac{4}{49}[(x-60)^2+40^2]\\\\\\(1-4/49)(x-60)^2=4*40^2/49=6400/49\\\\(45/49)(x-60)^2=6400/49\\\\45(x-60)^2=6400\\\\$

$x$

As $d_b=x$ , the lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

7 0

3 years ago