## anonymous 3 years ago What is an equation for the line that passes through points (–1, –4) and (1, 4)? Write the equation in slope-intercept form. (2 points)

1. anonymous

y = mx + b m=(y2-y1)/(x2-x1)

2. anonymous

@lolly wanna try

3. anonymous

no..but i will..:)

4. anonymous

(1,-4), m = -4 y = mx + b Sub to find b -4 = -4*1 + b b = 0 ------- y = -4x m = -4 means slope = -4. slope-intercept form of equation of a straight line is y = mx + b. m is the slope. b is the y-intercept. your equation starts of with the slope-intercept generic form of y = mx + b replace m with -4 to get y = -4x + b your line goes through the point (x,y) = (1,-4) that means the x-coordinate is 1 and the y coordinate is -4. to find the y-intercept, you replace y with -4 and x with 1 in the equation and solve for b. your equation of y = -4x + b becomes: -4 = (-4 * 1) + b

5. anonymous

can you set up the equation? then ill solve:P

6. anonymous

@swiftskier96 is that the answer http://www.algebra.com/algebra/homework/Graphs/Graphs.faq.question.233716.html hahaha

7. anonymous

(x1,y1) = (–1, –4) (x2,y2) = (1, 4)

8. anonymous

soo y=mx=b? isnt that for finding slope?

9. anonymous

yes but you need to find m 1st $y=\frac{ y2-y1 }{ x2-x1 }$

10. anonymous

meant m =

11. anonymous

ook ill try it..hold on..:)

12. anonymous

m=-6

13. anonymous

now what?

14. anonymous

show me how?

15. anonymous

m is wrong :D

16. anonymous

really?

17. anonymous

m= 1-4/-1--4. m=-3/3 m=-6

18. anonymous

(x1,y1) = (–1, –4) (x2,y2) = (1, 4) x1 = -1 y1 = -4 x2 = 1 y2 = 4

19. anonymous

hi lolly :P

20. anonymous

right..thats what i did..,.i think..?

21. anonymous

hi..:)

22. anonymous

(y-y1)/(y2-y1)=(x-x1)/(x2-x1)

23. anonymous

@surdawi how did i do it rong?

24. anonymous

(4- - 4)/(1- -1)= 8/2=4

25. anonymous

so m is 4?

26. anonymous

what you did (x2-y2)/(x1-y1)

27. anonymous

well i thought it was -6..but its not..?

28. anonymous

m = 4 now you choose wither point and solve for b y = 4x + b

29. anonymous

k hold on ill try again..:)

30. anonymous

$m=\frac{ y2-y1 }{ x2-x1 }=\frac{ 4- -4 }{ 1- -1 }=\frac{ 8 }{ 2 }=$

31. anonymous

for slope slope=(y2-y1)/(x2-x1) it can be directly solve see the formula that i have given already

32. anonymous

(y-y1)/(y2-y1)=(x-x1)/(x2-x1)

33. anonymous

oooh!!! i got the x1and 2s switched up..ok i see..:)

34. anonymous

|dw:1351797990809:dw|

35. anonymous

the one with less numbers right?

36. anonymous

there is no zeros for x or y this time so pick one and solve, it doesnt matter which one

37. anonymous

which one would be easier?

38. anonymous

either, same thing

39. anonymous

k ill do the one with less numbers..:P

40. anonymous

so 4=4x1=b? 4=b..but we already knew that..

41. anonymous

both of them has same amount of numbers :p 4=4x1=b? ! why is there an equal to b

42. anonymous

43. anonymous

so 4=4+4...

44. anonymous

4=8? that dosent make sense...

45. anonymous

4=4x1+ b what is x1 = ?

46. anonymous

-1

47. anonymous

y1 =?

48. anonymous

-1

49. anonymous

000h!!!

50. anonymous

no it dosent..:)

51. anonymous

-4

52. anonymous

it should be one of the pairs either (1,4) or (-1,-4) -4 = 4*(-1) + b

53. anonymous

-4=4x-1=4?

54. anonymous

4*-1=?

55. anonymous

-4

56. anonymous

-4 = -4 + b how can you keep b on one side?

57. anonymous

58. anonymous

ok show me how?

59. anonymous

-4=-4+b (then the 4 crosses out) +4 +4

60. anonymous

-4 +4 = -4 + 4 +b 0 = b y = 4x + 0

61. anonymous

where did the other set of -4=4 come from?

62. anonymous

you have to add 4 to both sides

63. anonymous

passes through points (–1, –4) and (1, 4)?

64. anonymous

65. anonymous

10.:)

66. anonymous

you should know how to add :P

67. anonymous

lol i do know how to add:)

68. anonymous

69. anonymous

lol @surdawi u sleeping?

70. anonymous

i went to pray |dw:1351801108941:dw|

71. anonymous

lol were u praying that id understand how to do this? lol jk ook umm anyway i thought b=4?

72. anonymous

lol muslims pray 5 times a day not only sundays :P ok plug in b = 4 to check y = 4*x + 4 (1, 4) 4 = 4*1 + 4 4 = 8? is that right

73. anonymous

4 is not 8...? im so confused!!

74. anonymous

thats would be the answer if b was 4 correct answer is y = 4x + 0 = 4x plug in and check and where is my medal at??

75. anonymous

do you want me to give you problem to do?

76. anonymous

try solving this What is an equation for the line that passes through points (2,5) and (6,7)? Write the equation in slope-intercept form. (you pay \$10 hehe)

77. anonymous

noo i dont want another problem im too stuck with this one..:)

78. anonymous

tell what you dont understand |dw:1351802673845:dw|

79. anonymous

i dont really understand what you did..like at all... for the one on the right side...

80. anonymous

ok (-1,-4) now we need to substitute that into y =mx + b y = -4 x = -1 m = 4 y = m* x + b -4 = 4*(-1) + b -4 = -4 + b we now need to add a 4 to both sides -4 = -4 + b +4 +4 -------------- 0 = 0 + b ===> b = 0

81. anonymous

ok so b = 4 and 0?

82. anonymous

no only 0 how do you get the 4?

83. anonymous

what we did earlier..

84. anonymous

we never got b = 4 we got m is 4

85. anonymous

oooh!!!

86. anonymous

i have to go to my Advance Engineering Math :( right now; which doesnt look like anything on here...try to figure it out; if you still have problems feel free to message me the answer is y = 4x

87. anonymous

k thanks 4 ur help:)

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