Question

Evaluate the limits. Use -∞ or ∞ where appropriate.

lim┬(x→-4)⁡((x+4)/(x^2-x-20))

Answer 1

I am getting... -4+4 on top which should be 0.
and -4^2-(-4)-20 on bottom. What????

Answer 2

So bottom would be 16+4 = 20 then 20-20 = 0 so it would be 0/0 right?

Which means it's undefined right?

Answer 3

or would I factor out the bottom?

Answer 4

Factor out the bottom to see if anything cancels out first.

Answer 5

I get (x-4)(x+5) so nothing cancels right.

Answer 6

I think your factoring is a bit off. check your signs.

Answer 7

-4+5 ≠ -1

Answer 8

so then it's (x+4)(x-5).... So the x+4 cancels.

Then I get 1/(x-5) if I plug in the -4 I get 1/9???

Answer 9

Right on. Good Job.

Answer 10

-9

Answer 11

so it's -1/9

Answer 12

yup