## anonymous one year ago WILL AWARD MEDAL AND WILL FAN HELP PLS What are the zeroes of f(x) = x2 − x − 2? x = −2, 1 x = 2, −1 x = −2, −1 x = 2, 1

1. anonymous

B

2. anonymous

How did you get that?

3. anonymous

Okay so I do these kinds of problems differently so tell me when you get lost okay?

4. anonymous

Okay

5. anonymous

|dw:1438386272376:dw| These do not mean fractions okay? They just mean to multiply. If you see the 1/2 that means 1*2 = 2 (the same 2 from the equation)

6. anonymous

Did you get that?

7. anonymous

Kind of

8. anonymous

Okay probably I should use the quadratic formula then

9. jdoe0001

hint: $$\large \begin{array}{ccllll} f(x)=x^2&-x&-2\\ &\uparrow &\uparrow \\ &-2+1&-2\cdot 1 \end{array}$$

10. Nnesha

okay so for that method factor out first and last term then cross multiply you should get the middle term

11. anonymous

Ya that's what I use @jdoe0001 but it's soo hard to explain that.

12. anonymous

I think I understand now

13. Nnesha

|dw:1438386492743:dw| it should 1 times -2 and don't forget the x

14. jdoe0001

@sofialauren I was going to ask for the autograph, but I notice is not sofia loren, so that's ok, but I'd settle for 2 binomials

15. anonymous

the quadratic formula: $\frac{ -b \pm \sqrt{b^2-4ac} }{ 2a }$

16. anonymous

$ax^2 + bx +c$

17. anonymous

Ugh... Another person to mix up our names

18. anonymous

And thanks guys

19. anonymous

I get it now

20. anonymous

Did you understand how to do it?

21. Nnesha

now cross multiply |dw:1438386562007:dw|

22. anonymous

You almost got it! There's no x after 2.

23. anonymous

Yes

24. Nnesha

who?

25. anonymous

Oh I see you were solving the blue circle in the picture above right?

26. anonymous

1x-2x=-x

27. anonymous

Lol @Nnesha I thought sofia drew that pic. Turns out it was you.

28. anonymous

You still there sofia?

29. anonymous

Yes

30. anonymous

Can you help me out with another question?

31. Nnesha

ohh okay i just explained the method you were doing nice!!

32. anonymous

Ya sure! And lol ya :)

33. anonymous

Factor x2 − 8x + 9. (x − 9)(x − 1) (x + 9)(x + 1) Prime (x + 9)(x − 1)

34. anonymous

Is it prime because it has an addition symbol?

35. anonymous

(x+1)(x-9)

36. anonymous

This is what I got but I don't see that answer....

37. anonymous

And what do you mean by prime?

38. anonymous

I don't know the exact definition

39. anonymous

Well prime is an exact number. Like 3/2 equals 1.5 that answer would be prime. but i don't know how equations can be prime.

40. anonymous

Unless it's (x+3)^2

41. anonymous

But it isn't

42. anonymous

(x+3)^2 might be prime I guess.....I'm not really sure.

43. anonymous

@Nnesha

44. anonymous

I tried distributing the answer choices to see if it would bring me back to the original equation

45. anonymous

Did any of them work?

46. anonymous

No

47. anonymous

Then I would choose prime especially if you know that the other choices don't work.

48. anonymous

@Nnesha do you know what they mean by prime in this problem?

49. Nnesha

well if leading coefficient is one then apply easy method *headphone* method :D find two number when you multiply them you should get product of AC and if you add or subtract them you should get middle term $\huge\rm Ax^2+Bx+C=0$ where a =leading coefficient b=middle term c= constant term

50. Nnesha

so in that question a=1 b=-8 c= 9 ac = 9 what two number you should multiply to get 9 BUT when you add them or subtract them you should get middle term which is -8

51. anonymous

52. Nnesha

good question hmm

53. Nnesha

sofia i guess :3

54. anonymous

Lol not trying to be obvious! :P Just wondering

55. Nnesha

prime means : when there is only *one* factor in other words a number which only divided by one

56. anonymous

Sorry I'm trying to multitask. I have to hurry so I'm trying to get everything done

57. Nnesha

there aren't any number you can multiply to get 9 and add or subtract to get middle term 9 times 1= 9 9-1= 8( but middle term is negative ) so 9 and 1 are not factors

58. anonymous

Okay

59. Nnesha

so that's the reason x^2-8x+9 is not factorable

60. anonymous

You can factor -9 and 1 though

61. Nnesha

okay multiply -9 times 1= -9 ( but we need POSITIVE 9 ) $\huge\rm x^2-8x\color{ReD}{+9}$

62. anonymous

Ohhhh!!! Lol sorry I didn't see that. Ya nnesha is right on that :)

63. anonymous

Sorry guys I have to go and I just put the answer as prime. Thank you for your help!

64. anonymous

No problem! :)