## Phebe one year ago HELPZZ http://prntscr.com/7sq0eu

1. laughoutloud

Do you know what two methods there are?

2. Phebe

No well one is the matrix method i think

3. Phebe

@Chumpian

4. laughoutloud

There is elimination and substitution

5. Phebe

okay thanks

6. Phebe

I just need to know how to do the problem

7. laughoutloud

ok for A) 3x-9y=3 6x-3y=-24 Solve the first equation for x

8. Phebe

ok so -9 on both sides?

9. laughoutloud

10. Phebe

ok like this|dw:1436908249151:dw|

11. laughoutloud

yes

12. Phebe

so 3+9=12|dw:1436908316517:dw|

13. Phebe

at the bottom those are 3's

14. laughoutloud

ok so the first equation look like this. 3x=3+9y

15. Phebe

Yes

16. laughoutloud

great so divide 3 by both sides

17. Phebe

ok hold on

18. Phebe

|dw:1436908667158:dw|

19. laughoutloud

k so when simplified we get x=1+3y

20. Phebe

where you get that from?

21. laughoutloud

|dw:1436908850564:dw|

22. Phebe

okay i see

23. Phebe

so what i do next

24. laughoutloud

plug the equation into the second one like this 6(1+3y)-3y=-24

25. Phebe

an then solve?

26. laughoutloud

yes solve for y

27. Phebe

ok

28. Phebe

|dw:1436909266839:dw| which one i isolate?

29. laughoutloud

ok so distribute out the 6

30. Phebe

|dw:1436909395652:dw|

31. laughoutloud

when you do that you get 6+18y-3y=-24

32. laughoutloud

|dw:1436909525038:dw|

33. Phebe

|dw:1436909655173:dw| right?

34. laughoutloud

no subtract the 6

35. Phebe

omg ok

36. Phebe

|dw:1436909740180:dw|

37. laughoutloud

|dw:1436909811890:dw|

38. Phebe

OH that kinda looks easy so the first equation is -2 right?

39. laughoutloud

no there's more lol y=-2 now plug in -2 for y in the first equation

40. Phebe

ok lol T.T

41. Phebe

Can you show me i dont know where to put it

42. laughoutloud

|dw:1436910047668:dw|

43. Phebe

so now i just put that the answer is -2 and -5?

44. laughoutloud

yes but write it like this (-5,-2)

45. Phebe

OKAY DANG THANK YOU! I BEEN WORKING ON THIS FOR 2 DAYS LOL

46. Phebe

can you help me with part B?

47. laughoutloud

sure

48. Phebe

thanksz! do u still got the problem?

49. laughoutloud

yes we are going to solve this one using elimination because it is quicker for this problem we solved the last one using substitution

50. Phebe

did we use elimination for the last one i think it was substitution

51. laughoutloud

no we used substituion

52. Phebe

OK i knew it thanksz

53. laughoutloud

we are going to solve this one together like this |dw:1436910768080:dw|

54. Phebe

thats matrix right?

55. laughoutloud

no the 3y cancels out

56. Phebe

|dw:1436911023546:dw| and then we just move over the rest of the problem?

57. laughoutloud

yes! add the two equations together like this |dw:1436911155428:dw|

58. Phebe

and then we put x=3 in the problem?

59. laughoutloud

yes plug it into either equation you can choose

60. Phebe

ok let me see

61. Phebe

|dw:1436911318766:dw|

62. laughoutloud

ok |dw:1436911428534:dw|

63. laughoutloud

64. Phebe

OMG!!!!!!!! THANK YOU!

65. laughoutloud

np do you want help with part c?

66. Phebe

OH yea i almost forgot lol

67. laughoutloud

lol We are going to solve this one using substitution

68. Phebe

ok ima put that

69. laughoutloud

I substituted y into the second equation |dw:1436911880872:dw|

70. Phebe

|dw:1436912011827:dw|

71. laughoutloud

not quite we have to distribute the 6 like this |dw:1436912140467:dw| I multiplied the six into the parenthesis

72. laughoutloud

now we can add 36 to each side

73. Phebe

|dw:1436912247899:dw| RIGHT

74. laughoutloud

yes

75. laughoutloud

76. Phebe

|dw:1436912323688:dw|

77. laughoutloud

Correct |dw:1436912410251:dw|

78. laughoutloud

now plug in the x value into the first equation

79. Phebe

ok

80. Phebe

|dw:1436912516544:dw|

81. laughoutloud

|dw:1436912554603:dw|

82. Phebe

so +6 on both ends right

83. laughoutloud

actually we can just solve this by multiplying 11 and (1/2) then subtracting 6 |dw:1436912738685:dw|

84. laughoutloud

so the answer to part c is |dw:1436912878418:dw|

85. Phebe

THANKSZZ!!

86. laughoutloud

No problem:)

87. Phebe

<3

88. Phebe

i should get a 100%

89. Phebe

well ima go so CYA~ thanks for all tha helpz

90. laughoutloud

Yep!

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