- #1
Wishingwell
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Homework Statement
I recently was counted off during a math quiz stating that I made a mistake in my arithmetic regarding the derivative of a function using the limit approach. (The long way with the lim h->0)
The equation was f(x) = -16x^2 + 20x and I was suppose to find f'(x) using the limit approach
Homework Equations
I am very sure I did everything right since my final answer was -32x + 20 but during my work there was one step he counted me off 1 letter grade for.
Doing the work you get down to a step that looks like this:
(-32xh - 16h^2 + 20h)/h
At this point I divided each term by h to get -32x -16h + 20 where I plugged in 0 for h.
However this was incorrect, it was apparently algebraically wrong as I was suppose to factor out an h from each term and then divide by h. I have always been taught to divide by h and assumed this was is an acceptable way to do it.
Was it any wrong to lose credit for dividing by h instead of factoring and then dividing? If not, can anyone explain and I can maybe send this to my professor to get some credit back.
The Attempt at a Solution
See above