## juciystar234 3 years ago 8- 6.2 divided by 5 + 7(0.91) help me please

1. niduj123

13.3

2. juciystar234

My textbook says 13.13 so I was wondering how they got that. Can you show me/ Tell me how you got that answer because I'm kinda confused...

3. niduj123

its easy bc its basic order of operations

4. juciystar234

Yeah I know NVM :) thanks

5. niduj123

can i hav a medal o.O

6. niduj123

tyvm

7. juciystar234

np

8. asnaseer

for this:$\frac{8- 6.2}{5 + 7(0.91)}$ you need to follow BODMAS - have you heard about that?

9. asnaseer

it is known by other names as well, see here: http://en.wikipedia.org/wiki/Order_of_operations

10. juciystar234

Ok let me check it out hold on

11. asnaseer

look at the 2nd section "The standard order of operations"

12. juciystar234

Ok hold on hmm SO MANY WORDS!! D:

13. niduj123

lol typical wikipedia

14. juciystar234

Ok I kinda got it

15. juciystar234

(not really so much)

16. niduj123

kwl i hope u pass :)

17. asnaseer

good - so first thing to attack is the brackets

18. juciystar234

Thanks

19. juciystar234

Ok

20. niduj123

^^...

21. asnaseer

in this case the brackets just contain a number - so no actual operation to perform inside the brackets

22. juciystar234

ok

23. asnaseer

we can therefore remove the brackets to end up with:$\frac{8- 6.2}{5 + 7(0.91)}=\frac{8- 6.2}{5 + 7*0.91}$

24. juciystar234

:p

25. juciystar234

Mhm ok

26. juciystar234

hmmm ok im confused...

27. asnaseer

lets jus concentrate on the denominator for now, we had:$5+7(0.91)$correct?

28. juciystar234

yes

29. asnaseer

now note that a(b) simply means a*b - agreed?

30. juciystar234

ok

31. juciystar234

agreed

32. asnaseer

so we can say that:$5+7(0.91)=5+7*0.91$

33. asnaseer

does that make sense now?

34. juciystar234

ok got tht

35. juciystar234

yes

36. asnaseer

good - now what should the next set of operations be?

37. asnaseer

we have handled the brackets

38. juciystar234

um to multiply?>

39. juciystar234

sorry didnt mean to put >

40. asnaseer

it should be exponents and roots next - but you do not have any here so we go to the next one: multiplication an division

41. juciystar234

Yea!! Ok

42. asnaseer

so what is 7 * 0.91 = ?

43. juciystar234

Um hold on

44. juciystar234

6.37

45. asnaseer

correct, so now we end up with:$\frac{8- 6.2}{5 + 7(0.91)}=\frac{8- 6.2}{5 + 7*0.91}=\frac{8- 6.2}{5 + 6.37}$now most people get confused here because they think the next thing to do is the division

46. juciystar234

47. juciystar234

48. asnaseer

but what you need to remember is that you go through BODMAS for the numerator and the denominator seperately

49. juciystar234

ok

50. asnaseer

51. asnaseer

I believe it was this instead:$8- 6.2 \div 5 + 7(0.91)$

52. asnaseer

am I right?

53. juciystar234

yes

54. juciystar234

wait

55. juciystar234

yes

56. asnaseer

ok, sorry I originally interpreted it as:$$(8- 6.2) \div (5 + 7(0.91))$$

57. juciystar234

ohhh ok

58. asnaseer

so lets start again - ok?

59. juciystar234

ok

60. asnaseer

$8- 6.2 \div 5 + 7(0.91)$first step - brackets to get:$8- 6.2 \div 5 + 7(0.91)=8- 6.2 \div 5 + 7*0.91$next is exponents/root but we have none next is multiplication/division - we have both, so you did 7*0.91 = 6.37$8- 6.2 \div 5 + 6.37$

61. asnaseer

thats how far we got

62. asnaseer

so next we should do what?

63. juciystar234

64. juciystar234

or no subtract

65. asnaseer

nope - have a closer look at what is still left

66. juciystar234

like left to right but switch add with division

67. asnaseer

it should be division next

68. juciystar234

so divide?

69. juciystar234

ok

70. asnaseer

so what is 6.2 divided by 5 = ?

71. juciystar234

ok hold on

72. asnaseer

(a quick trick to divide by 5 is to divide by 10 and then halve the result)

73. juciystar234

|dw:1347581921786:dw|

74. juciystar234

sorry i was drawing :P

75. asnaseer

that is not correct

76. juciystar234

o.o

77. juciystar234

ok :) so now how do i do it ? :|

78. asnaseer

the /quick/ method or using long division like you attempted up there?

79. juciystar234

or like were did i mess up

80. juciystar234

um i guess....

81. juciystar234

go on

82. asnaseer

|dw:1347582167712:dw|

83. juciystar234

oh

84. juciystar234

i get it!!!

85. juciystar234

my decimal messed me up..

86. asnaseer

the other way is 6.2 divided by 10 is 0.62 double that is 0.62 + 0.62 = 1.24 (sorry I incorrectly stated you halve the result up there - it should be double the result after dividing by 10)

87. juciystar234

Hmmm ok

88. asnaseer

ok, so we now have:$8- 6.2 \div 5 + 6.37=8-1.24+6.37$

89. asnaseer

the rest should now be straight forward

90. juciystar234

91. asnaseer

sure

92. juciystar234

ok

93. asnaseer

but be careful with the signs

94. juciystar234

I got this part let me draw it for you

95. juciystar234

|dw:1347582462471:dw|

96. asnaseer

remember the 1.24 has a minus sign next to it

97. asnaseer

so this is really "-1.24 + 6.37"

98. juciystar234

no thats not a negative its a minus

99. asnaseer

so it might be better to first do "8 - 1.24"

100. juciystar234

ok

101. juciystar234

6.76?

102. juciystar234

103. asnaseer

think of it in this way:$8- 6.2 \div 5 + 6.37=8-1.24+6.37=8+(-1.24)+6.37$

104. asnaseer

105. juciystar234

ok so 13.13

106. asnaseer

I was trying to explain why you had to do "-1.24 + 6.37" previously

107. juciystar234

Yaaa i got it my text book says that but i needed to work it out thank you!!!!!

108. asnaseer

yes - that is the correct answer

109. juciystar234

ok

110. asnaseer

yw :)

111. juciystar234

Thanks once again!! :D

112. asnaseer

np :)