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Find the instantaneous rate of change for the function f(x) = 5x^2 + x at x = -4.

I am getting -14, but I can see how it could be -41 too. What am I doing?
 
baseballpro040 said:
What am I doing?
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Until you post your steps (the ones by which you got the two different answers), I'm afraid we cannot know what you're doing.

Thank you.

Eliz.
 
No idea, mate; you need to show your work: what was your derivative?

Although your second answer kind of looks like your derivative had a minus where it shouldn't have.
 
I did it three times and got -12, 18, and \(\displaystyle \sqrt{3}\). Of course, I deliberately made errors on all three tries.

We cannot settle it by a vote. The student must show the process.

baseballpro040, you have the bat in hand. What will you do with it? Tell us what you are doing. If you can "see" two solutions, you clearly do not understand what you are doing. There is a unique answer.
 
tkhunny said:
If you can "see" two solutions....
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This may be another one of what we've seen so much of lately: The student has been provided with a multiple-choice question, and is asking "Is it (a)? Is it (b)?..." until he hears a "yes".

Eliz.
 
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