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What is the average rate of change for this quadratic function for the intervalfrom x=2 to x = 4?A. -12B. 6C. -6D. 12

What is the average rate of change for this quadratic function for the intervalfrom-example-1
User Technoplato
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1 Answer

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22 votes
Average rate of change of a function

Initial explanation

We know that the average rate of change of a function between the point

x = a

and the point

x = b

is given by the formula:


(f(b)-f(a))/(b-a)=(\Delta y)/(\Delta x)

This is how much the function changed on the y axis divided by the change in the x axis.

For this quadratic function...

In this case, we have that the points a and b are x = 2 and x = 4:

We can observe that

when x = 2

then f(2) = -3

when x = 4

then f(4) = -15

Then, using the formula, we have:


\begin{gathered} (f(b)-f(a))/(b-a)=(\Delta y)/(\Delta x) \\ \downarrow \\ (f(4)-f(2))/(4-2)=(-15-(-3))/(2) \\ =(-12)/(2)=-6 \end{gathered}

Answer: C. -6

What is the average rate of change for this quadratic function for the intervalfrom-example-1
User KingJackaL
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