Limits of t^2-9/t-3: Factoring & Substitution

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SUMMARY

The limit of the expression (t^2 - 9)/(t - 3) as t approaches 3 can be evaluated by factoring the numerator into (t - 3)(t + 3) and canceling the (t - 3) terms. This cancellation is valid because the limit process allows for the assumption that (t - 3) is not equal to zero as t approaches 3. Substituting t = 3 into the simplified expression yields a limit of 6.

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Homework Statement




lim t^2-9/t-3
x>3

Homework Equations





The Attempt at a Solution



I factored it into (t-3)(t+3)/(t-3)
i then canceled out the (t-3)'s and substituted 3 to get 6 is this correct?
 
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Assuming you made a typo and your problem is the limit as t -> 3, then yes, what you did is correct. You can only ever cancel an expression with a variable (such as (t-3)) if you are sure that it is not going to be zero. In this case, we are taking the limit as t goes to 3, so (t-3) is never actually equal to 0. Thus, we can cancel (t-3) and you are correct.
 
Thanks!
 

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