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Evaluating the Difference Quotient

  • #1

Homework Statement


Evaluate the difference quotient of:
f(1+h)-f(1) / h
if f(x)=x3
and simplify your answer.

Homework Equations



The Attempt at a Solution


I took the derivative of x3 to be 3x2 and solved for when x=1 (given from the difference quotient) and got 3, but when I enter the value it's marked incorrect. Not sure what I'm doing wrong, unless I just interpreted the question the wrong way.
 

Answers and Replies

  • #2
pasmith
Homework Helper
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Homework Statement


Evaluate the difference quotient of:
f(1+h)-f(1) / h
if f(x)=x3
and simplify your answer.

Homework Equations



The Attempt at a Solution


I took the derivative of x3 to be 3x2 and solved for when x=1 (given from the difference quotient) and got 3, but when I enter the value it's marked incorrect. Not sure what I'm doing wrong, unless I just interpreted the question the wrong way.
Calculate [itex]((1 + h)^3 - 1^3)/h[/itex] and do not take the limit [itex]h \to 0[/itex].
 
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  • #3
Ah, okay. Got h^2+3h+3, entered it and it was correct. Thanks! I'm not sure why I thought it was asking for the limit, guess I'm still a little fuzzy from the summer.
 

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