## anonymous one year ago What is the discontuinty of f(x) = the quantity negative x squared plus x plus 20 over the quantity x plus 4?

1. anonymous

@Astrophysics

2. anonymous

|dw:1437190829325:dw|

3. anonymous

So I think it is -4?

4. anonymous

Am I right?

5. Astrophysics

So you're taking $\lim_{x \rightarrow -4} f(x)$

6. anonymous

Um..I suppose:).

7. Astrophysics

Mhm, you know calculus?

8. anonymous

No. It's Algebra 2

9. Astrophysics

But yes, that's right -4

10. Astrophysics

As the domain is all real numbers where x cannot equal -4.

11. Astrophysics

So you're looking for what x is basically then, so factor the top, that should give it away :)

12. Astrophysics

To find the zeros you have to factor the numerator, it's just finding the roots, hence x.

13. anonymous

So (x-4)(x+5)

14. anonymous

do I just plug in -4?

15. Astrophysics

You should've got -(x+4)(x-5)

16. anonymous

So it is (-4,1)

17. Astrophysics

Then you can cancel out the numerator and denominator of (x+4) and you'll have x = 5 as your zero

18. anonymous

So, if I were to graph it, the point would be -4,1 ? Correct?

19. anonymous

Is it working now?

20. Astrophysics

Oh I see what you mean now, so if we take the limit we would indeed get = 9

21. Astrophysics

I really can't remember doing it in algebra 2, mhm I will have to do some research

22. anonymous

haha<3 Ok! Thank-you:)

23. anonymous

What is the graph of the function f(x) = the quantity of negative x squared minus 2 x minus 2, all over x minus 2?

24. Astrophysics

use this site to graph https://www.desmos.com/calculator

25. anonymous

I don't mean to post another question because usually I can figure things out by myself, but I can't graph usind desmos. It won't work

26. anonymous

Maybe I'm doing it wrong. Because when I typed it in, I only got one graph when it should have been two. Like 2 lines:)

27. anonymous

Any thoughts?

28. Astrophysics

Well, you can't put words if that's what you're trying, so what do those words tell us mathematically?

29. anonymous

-x^2-2x-2/x-2

30. anonymous

And I didn't :) I typed in that

31. Astrophysics

I got this, make sure you put y = , or f(x) = |dw:1437192565745:dw|

32. anonymous

Ok:) But shouldn't there two?

33. anonymous

Nevermind! Thank-you<3

34. Astrophysics

Np ^.^

35. anonymous

$A\ function\ f(x)\ is\ said\ tobe\ continuous\ at\ a\ point\ x=c \ of\ its\ domain\\ \iff\ \lim_{x \rightarrow c}=f(c).$