Compare the estimated average rates of change of the functions f(x)=3x−4−−−−−√ and g(x)=2x−43−−−−−√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 use the formula for average rate of change:

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

where \( a = 2 \) and \( b = 3 \).

Let's calculate the average rate of change for \( f(x) \) first.

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 can find the estimated average rates of change:

  • Average rate of change of \( f \) is \( \sqrt{5} - \sqrt{2} \).
  • Average rate of change of \( g \) is \( \sqrt[3]{2} \).

Convert the results into decimal approximations:

  • Approximately,
    • \( \sqrt{2} \approx 1.414 \)
    • \( \sqrt{5} \approx 2.236 \)
    • Hence, \[ \sqrt{5} - \sqrt{2} \approx 2.236 - 1.414 \approx 0.822 \]
  • For \( g \),
    • \( \sqrt[3]{2} \approx 1.26 \)

Finally, state the difference in the estimated average rates of change:

\[ \text{Difference} = |\text{Average Rate of Change of } f - \text{Average Rate of Change of } g| \approx |0.822 - 1.26| \approx | -0.438 | \approx 0.438 \]

Now, rounding \( 0.438 \) to the nearest tenth gives us \( 0.4 \).

Therefore, the difference in the estimated average rates of change to the nearest tenth is:

\[ \boxed{0.4} \]