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If y= (x^2+20)/(x-4) Find all critical Numbers.

After get f' i got the answer -5/4. What did i do wrong or is that the critical number?

  • math -

    critical number: where y'=0 or y' undefined.

    Anyway, y' = (x^2-8x-20)/(x-4)^2

    y'=0 when x = -2,10
    y' undefined when x = 4

    how did you come up with -5/4 ?

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