Need help with slope of secant line to f(x) = 3x^2 through

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tkthustler

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f (x) = 3x^2

The slope of the secant line through the points (2,f(2)) and 5,f(5)) on the graph y=f(x).

I try reading the book but I just dont understand the terms when they use all of this variable talk. I'm just trying to figure out which numbers go where but I just dont get this stuff.
 
this is called the average rate of change of the function on the interval [2,5].

average rate of change = slope of the secant line = [f(5) - f(2)]/(5 - 2)

now ... determine f(5) and f(2) and calculate the average rate of change.
 
Um.. I plugged in the numbers and got 23...but thats not right...

is that the answer if they just asked for the average rate of change from 2-5??
 
yes, that's not right.

f(x) = 3x^2

f(5) = 3*5^2 = 3*25 = 75

f(2) = 3*2^2 = 3*4 = 12

(75 - 12)/(5 - 2) = 63/3 = 21
 
I thought thats how you worked out the problems that stated AVerage rate of change from 5 to 2. How is that problem different then the secant line problems.
 
I did, but I guess I'm confused. Are they the same thing. Average rate of change and slope of the secant line?
 
OOOO ok, sry skeeter.. still real new at all this. Thanks for your help.

-Brian
 
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