## AudrianaS 3 years ago Find the x-intercepts: 2(x-5)^2=17

1. manishsatywali

x= [17/2]^1/2 +5|dw:1345790422320:dw|

2. dpaInc

x-intercepts? this is an equation in one variable.... how do you do that?

3. panlac01
4. AudrianaS

Am I suppose to distribute the 2?

5. dpaInc

ahh.... my bad.... because this is an equation in one variable, it is just a vertical line.... so solving for x will give you the only x-intercept....

6. panlac01

since this is a quadratic function, you will get 2 values for the x-intercepts. read pp 126-129 in the link I've posted above.

7. RolyPoly

2 x-intercepts? $2(x-5)^2=17$Divide both sides by 2$(x-5)^2=\frac{17}{2}$Take square roots for both sides $(x-5)=\pm \frac{17}{2}$Add 5 to both sides to get the answer.

8. RolyPoly

I'm always late....

9. AudrianaS

oh okay thank you that makes so much sense :)

10. dpaInc

hold on folks... this is an equation in x only.... this is a vertical line.... and not a function.... "Find the x-intercepts: 2(x-5)^2=17"

11. RolyPoly

Wow. That's complicated. I thought all I had to do was to solve it but seems not :(

12. dpaInc

this is a function: y = 2(x-5)^2 this is not a function: 17 = 2(x-5)^2

13. panlac01

parabolas always have 2 x-intercepts unless k=0, is it not?

14. RolyPoly

But how to get the x-intercept(s)??? There is no y...

15. dpaInc

in any function, to find the x-intercepts, set y=0 and solve.... how are you gonna set y=0 in the equation 2(x-5)^2 =17 ????

16. razor99

Think the x-intercept is 8.5,0

17. RolyPoly

Perhaps this would be the case? y = 2(x-5)^2-17 Put y=0 2(x-5)^2-17 = 0 2(x-5)^2=17 . . . Solve x to find the x-intercepts. Hmm...

18. panlac01

dpalnc solved it, x=5 - sqrt(17/2) x=5+ sqrt(17/2)

19. dpaInc

compare these two equations: y = x + 3 and 17 = x + 3 that first one is a line and you can find the x-intercept by setting y=0 then solving 0 = x + 3. but that second equation is just a vertical line....

20. RolyPoly

Eh?! Then, for 17=x+3, the x-intercept is 17-3 = 14?!

21. lgbasallote

you have been trolled

22. dpaInc

dang this chrome browser.... x = 14 is a vertical line and that's where it crosses the x-axis.... but back to the problem... did i say 1 x-intercept? i mean two as panlac says.... :)

23. panlac01

LOL

24. lgbasallote

a vertical line that curves...obviously troll ^^

25. dpaInc

how 'bout two vertical lines... it's implied when u solve a quadratic you have to consider the positive and negative square root....

26. lgbasallote

^trOWL

27. dpaInc

yeah buwahhahahahaha

28. dpaInc

ang troll ^^^

29. lgbasallote

this goes against the teachings of the monks... the forefathers defined x-intercept as "the value of y when x is 0" however, there is no y....

30. lgbasallote

this is not a function

31. dpaInc

right... so when you solve for x in that equation, you get two vertical lines... an equation in only 1 variable x is not a function...

32. lgbasallote

no. this is just not a function. nothing more; nothing less

33. lgbasallote

it's a relation, but not a function

34. lgbasallote

x-intercepts occur in function only

35. dpaInc

when did i say it is a function?

36. panlac01

I said it was, my mistake

37. lgbasallote

you were saying it had an x-intercept

38. panlac01

two values for x...

39. lgbasallote

it has values for x...but no x-intercept

40. dpaInc

but the vertical line intercepts the x-axis...

41. panlac01

yes. LG you are right

42. lgbasallote

http://mathworld.wolfram.com/x-Intercept.html "The point at which a curve or FUNCTION crosses the x-axis (i.e., when in two dimensions)."

43. lgbasallote

like i said. you got trolled

44. panlac01

cross or touches...

45. dpaInc

so are you saying that a circle (which is a curve) does not have x-intercepts?

46. lgbasallote

yes it doesnt. it's not a function

47. panlac01

circle is not a function

48. lgbasallote

neither do ellipses

49. panlac01

function = 1 to 1 value

50. dpaInc

so why can't you call the where a vertical line crosses the the x-axis the x-intercept?

51. lgbasallote

any closed figure is not a function. it is a plane

52. panlac01

this is going beyond the problem now... bottom line: x has two values

53. dpaInc

i agree to agree... if that makes sense....

54. dpaInc

hey LG... i thnk u scared off the asker.... or he/she got bored...

55. panlac01

did she ask the problem to be graphed?

56. panlac01

lol jk. let us just leave it

57. lgbasallote

i would like to quote myself "you got trolled" relations have x-intercepts too http://en.wikibooks.org/wiki/Algebra/Intercepts

58. dpaInc

yes.... let's graph it....

59. panlac01

this is really going beyond now... why can't we agree that the intercepts are where either the vertical line or horizontal line are touched or crossed? did I start the fire when I said it was a function? I retracted it so OS can be a better place for students once again...

60. dpaInc

sorry man... i just miss talkin to LG....

61. dpaInc

u know u'd make a great ambassador for keeping the peace....:)

62. dpaInc

so peace to everyone.....:)

63. panlac01

I'd be damned...

64. dpaInc

lol...