## anonymous one year ago What is the equation of the line, in point slope form, that passes through the given point and has the given slope? point: (8,-8) and slope 3 a. y-8=3(x+8) b. y+8=3(x+8) c. y-8=3(x-8) d. y+8=3(x-8) What are the intercepts of the equation? 5x+3y=15 what is the equation of the line perpendicular to the line y= 4/9 x - 2 that passes through point (4,3) a. y= -4/9 x -2 b. y= 9/4 x + 6 c. y= -9/4 x + 12 d. y= -9/4 x - 12 i really need help, please help

1. LynFran

2. anonymous

okay

3. LynFran

we are given points (8,-8) and slope 3 to put in point slope form|dw:1441393907189:dw|

4. anonymous

so would i distribute ?

5. LynFran

yes

6. LynFran

only the negative sign

7. LynFran

which option would we get?

8. anonymous

hold on oneee second im almost done

9. anonymous

wait so for y-(-8) how woould i distribute that, would it be just be -8y?

10. LynFran

|dw:1441394211850:dw|

11. anonymous

so it would be 8y= 3x - (-) 24?

12. LynFran

no ... u just need to distbute the 2 negative signs here|dw:1441394401381:dw|

13. anonymous

ohhhhhh okay

14. LynFran

i this case to match the given options the 2 negatives will make positive when....

15. LynFran

16. anonymous

its y+8 = 3 (x-8) so D

17. LynFran

yes

18. anonymous

thank you

19. anonymous

what is the equation of the line perpendicular to the line y= 4/9 x - 2 that passes through point (4,3) Refer to the attachment from Mathematica.

20. anonymous

i dont understand that @robtobey

21. LynFran

question 2 intercepts to find the x-intercept we let y=0 to find the y-intercept we let x=0 but first we solve the given equation.. 5x+3y=15 lets solve for y 3y=15-5x y=(-5x+15)/3 now find the x intercept.... 0=(-5x+15)/3

22. anonymous

you took the 3 away from y to solve for it butbwhy did you put it into the equation to divide. dont we cancel something out?

23. LynFran

since the 3 was being multiplied to y....3y ...to get the y term alone we divide by 3...and since its an equation...what we do to the left side we must do the same to the right side ...

24. anonymous

ohh okay okay i gotchu

25. LynFran

so wats the x-intercept?

26. anonymous

0?

27. LynFran

nope

28. anonymous

3?

29. LynFran

0=(-5x+15)/3

30. anonymous

i give up

31. LynFran

0*3=(-5x+15)/3*(3)...the 3 will cancel on the right side 0=-5x+15 0+5x=-5x+5x+15 5x=15 x=15/5 x=3 the x-intercept (3,0)

32. anonymous

okay i understand it better i guess its still a little confusing but ill look over some more later

33. LynFran

lets solve the y-intercept y=(-5(0)+15)/3 y=(0+15)/3 y=15/3

34. LynFran

so the y-intercept is?

35. anonymous

would it be 5

36. LynFran

plz put it in point form

37. LynFran

like (x,y)

38. anonymous

okay soo (0,5)

39. LynFran

yes

40. anonymous

yayy

41. LynFran

Do u want me to do the 3rd question...or..its ok...

42. anonymous

yeah because the way that guy did it really confused me

43. LynFran

ok when two lines are perpendicular their slopes=-1 in other words the product of there slope =-1

44. LynFran

our equation y=4/9x-2 with point (4,3)

45. LynFran

can u tell me the slope for that equation

46. anonymous

no because i have no clue whats going on

47. LynFran

y=mx+b where m is the slope and b is the y-intercept

48. anonymous

m is 4/9x and b is -2?

49. LynFran

m=4/9

50. LynFran

so |dw:1441396731186:dw|

51. LynFran

whats our new slope?

52. anonymous

would it be -4/9?

53. LynFran

|dw:1441396920476:dw|

54. LynFran

|dw:1441397063320:dw|

55. anonymous

so it would be -9/4x

56. LynFran

so we have our new slope m=-9/4 and points (4,3)

57. anonymous

58. LynFran

yes

59. LynFran

do u have any question?....

60. anonymous

no, thank you so much for helping me !!!

61. LynFran

ok welcome