Finding Critical Numbers - Example 1

Finding Critical Numbers - Example 1. In this video I show how to find the critical numbers of a rational function.
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Category:

Education

Tags:

• math
• calculus
• critical
• numbers
• find
• finding
• example
• increasing
• decreasing
• interval
• test
• local
• maximum
• justmathtutoring

[moonira0209]

What does he mean by domain? Wats the domain here?

[patrickJMT]

@moonira0209 the domain of the function... videos on that too : )

[vindrila]

I should make "Thank you" auto comment for your videos ;)

[patrickJMT]

@vindrila ha : )

[iixsarah]

but arent critical numbers x-values such that f'(x)=0 and/or f'(x)=undefined? so why can't -3 and 3 work? if you plug it into the derivative, it's undefined..

[patrickJMT]

@iixsarah the values also have to be in the domain of the original function. this is the part no one remembers!

[patrickJMT]

very few teachers are over paid

[dassix1]

Thank you patrick. What makes your vidoes especially good is how neat and clean your work is, in comparison to the rest of the videos floating around youtube. Thank you for all your work.

[wolf0805]

What is an example of when it is undefined and in the domain?

[reedOsama]

@iixsarah the derivative f '(x) needs to be undefined but if you plug 3 and -3 into the original equation f(x) it's also undefined which means it doesn't exist on the graph... at least that's how I understand it.

[patrickJMT]

@brittnibeers you should read the definition a bit closer for critical numbers.

[brittnibeers]

I DON'T UNDERSTAND WHY ISN'T 3 AND -3 ACCEPTED. Critical numbers are defined as f'(x)=undefined so why why WHYYY ;A;