Compare the estimated average rates of change of the functions f(x)=3x−4−−−−−−√

and g(x)=2x−4/3 (this is a fraction)−−−−−√3
over the interval [2,3]
. State the difference in the estimated average rates of change to the nearest tenth

1 answer

To find the estimated average rates of change of the functions \( f(x) = \sqrt{3x - 4} \) and \( g(x) = \sqrt[3]{2x - 4} \) over the interval \([2, 3]\), we will use the formula for the average rate of change of a function over an interval \([a, b]\):

\[ \text{Average Rate of Change} = \frac{f(b) - f(a)}{b - a} \]

For \( f(x) = \sqrt{3x - 4} \):

  1. Calculate \( f(2) \): \[ f(2) = \sqrt{3(2) - 4} = \sqrt{6 - 4} = \sqrt{2} \]

  2. Calculate \( f(3) \): \[ f(3) = \sqrt{3(3) - 4} = \sqrt{9 - 4} = \sqrt{5} \]

  3. Calculate the average rate of change: \[ \text{Average Rate of Change of } f = \frac{f(3) - f(2)}{3 - 2} = \frac{\sqrt{5} - \sqrt{2}}{1} = \sqrt{5} - \sqrt{2} \]

For \( g(x) = \sqrt[3]{2x - 4} \):

  1. Calculate \( g(2) \): \[ g(2) = \sqrt[3]{2(2) - 4} = \sqrt[3]{4 - 4} = \sqrt[3]{0} = 0 \]

  2. Calculate \( g(3) \): \[ g(3) = \sqrt[3]{2(3) - 4} = \sqrt[3]{6 - 4} = \sqrt[3]{2} \]

  3. Calculate the average rate of change: \[ \text{Average Rate of Change of } g = \frac{g(3) - g(2)}{3 - 2} = \frac{\sqrt[3]{2} - 0}{1} = \sqrt[3]{2} \]

Now we have:

  • Average Rate of Change of \( f = \sqrt{5} - \sqrt{2} \)
  • Average Rate of Change of \( g = \sqrt[3]{2} \)

Next, we will compute the numerical values of these average rates of change:

  1. Calculate \( \sqrt{5} - \sqrt{2} \):

    • \( \sqrt{5} \approx 2.236 \)
    • \( \sqrt{2} \approx 1.414 \)
    • \( \sqrt{5} - \sqrt{2} \approx 2.236 - 1.414 \approx 0.822 \)
  2. Calculate \( \sqrt[3]{2} \):

    • \( \sqrt[3]{2} \approx 1.2599 \)

Finally, we find the difference between the two average rates of change:

\[ \text{Difference} = |\sqrt{5} - \sqrt{2} - \sqrt[3]{2}| \approx |0.822 - 1.2599| \approx | -0.4379| \approx 0.4379 \]

Rounding this to the nearest tenth gives:

\[ \text{Difference} \approx 0.4 \]

Thus, the difference in the estimated average rates of change to the nearest tenth is \( \boxed{0.4} \).