Question

Don't know where to start. Find all numbers for which the rational expression is undefined.
t^3-4t/t^2-81
thanks

Answer 1

its undefined when the bottom of the fraction = 0

Answer 2

i see i difference of squares under there

Answer 3

basically, when t= +-9 it goes bad real fast

Answer 4

ok..shaky but i understand a little better

Answer 5

t^3-4t
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t^2-81 <-- if this part = 0; it is undefined 1/0 is bad