- #1
duncanrager
- 2
- 0
I am a little confused about when to use the quotient rule. When you have one function over another function, and are taking the derivative, are you required to use this technique? I thought you were, but then I was watching this video on Khan Academy...
https://www.khanacademy.org/math/ca...ns/lhopital_rule/v/l-hopital-s-rule-example-2
...and the instructor, Sal, did not use the quotient rule. You don't even need to watch the video, the screenshot at the beginning shows exactly what he did. Using L'Hopital's rule, he simply took the derivative of the function in the numerator using the power rule, and did the same to the denominator.
If you don't want to follow the link, the problem was...
Take the limit as x approaches infinity of: (8x-5)/-6x
He couldn't evaluate the limit by replacement because you get infinity over negative infinity... so he used L'Hopital's rule and got 8/-6.
Why didn't he have to use the quotient rule? How is this problem different from any others?
Thanks so much,
Colin
https://www.khanacademy.org/math/ca...ns/lhopital_rule/v/l-hopital-s-rule-example-2
...and the instructor, Sal, did not use the quotient rule. You don't even need to watch the video, the screenshot at the beginning shows exactly what he did. Using L'Hopital's rule, he simply took the derivative of the function in the numerator using the power rule, and did the same to the denominator.
If you don't want to follow the link, the problem was...
Take the limit as x approaches infinity of: (8x-5)/-6x
He couldn't evaluate the limit by replacement because you get infinity over negative infinity... so he used L'Hopital's rule and got 8/-6.
Why didn't he have to use the quotient rule? How is this problem different from any others?
Thanks so much,
Colin