Given the function f(x) = 4x + 1, EXPLAIN and show how to find the average rate of change between x = 1 and x = 3.

Average rate of change is another word for the slope. The function you have is presented in slope-intercept form (y=mx+b), where m=your slope. This means that you already know the slope, which is 4.

Just in case you need to show why the slope = 4, I’ll leave how to find it here:

To find the slope, use the formula: y2-y1/x2-x1

First, you need to find the y-values at x=1 and x=3. To do this, plug the x-values into the equation. The value you end up with is your y-value.

f(1) = 4(1) + 1 = 5
f(3) = 4(3) + 1 = 13

So your two points are (1, 5) and (4, 13). Now plug these points into the slope formula

m = (13-5)/(3-1) = 8/2. 8 divided by two is 4, so your average rate of change is 4. You can double check this by graphing.

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