## anonymous 4 years ago 8- 6.2 divided by 5 + 7(0.91) help me please

1. anonymous

13.3

2. anonymous

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. anonymous

its easy bc its basic order of operations

4. anonymous

Yeah I know NVM :) thanks

5. anonymous

can i hav a medal o.O

6. anonymous

tyvm

7. anonymous

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. anonymous

Ok let me check it out hold on

11. asnaseer

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

12. anonymous

Ok hold on hmm SO MANY WORDS!! D:

13. anonymous

lol typical wikipedia

14. anonymous

Ok I kinda got it

15. anonymous

(not really so much)

16. anonymous

kwl i hope u pass :)

17. asnaseer

good - so first thing to attack is the brackets

18. anonymous

Thanks

19. anonymous

Ok

20. anonymous

^^...

21. asnaseer

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

22. anonymous

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. anonymous

:p

25. anonymous

Mhm ok

26. anonymous

hmmm ok im confused...

27. asnaseer

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

28. anonymous

yes

29. asnaseer

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

30. anonymous

ok

31. anonymous

agreed

32. asnaseer

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

33. asnaseer

does that make sense now?

34. anonymous

ok got tht

35. anonymous

yes

36. asnaseer

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

37. asnaseer

we have handled the brackets

38. anonymous

um to multiply?>

39. anonymous

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. anonymous

Yea!! Ok

42. asnaseer

so what is 7 * 0.91 = ?

43. anonymous

Um hold on

44. anonymous

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. anonymous

47. anonymous

48. asnaseer

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

49. anonymous

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. anonymous

yes

54. anonymous

wait

55. anonymous

yes

56. asnaseer

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

57. anonymous

ohhh ok

58. asnaseer

so lets start again - ok?

59. anonymous

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. anonymous

64. anonymous

or no subtract

65. asnaseer

nope - have a closer look at what is still left

66. anonymous

like left to right but switch add with division

67. asnaseer

it should be division next

68. anonymous

so divide?

69. anonymous

ok

70. asnaseer

so what is 6.2 divided by 5 = ?

71. anonymous

ok hold on

72. asnaseer

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

73. anonymous

|dw:1347581921786:dw|

74. anonymous

sorry i was drawing :P

75. asnaseer

that is not correct

76. anonymous

o.o

77. anonymous

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

78. asnaseer

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

79. anonymous

or like were did i mess up

80. anonymous

um i guess....

81. anonymous

go on

82. asnaseer

|dw:1347582167712:dw|

83. anonymous

oh

84. anonymous

i get it!!!

85. anonymous

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. anonymous

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. anonymous

91. asnaseer

sure

92. anonymous

ok

93. asnaseer

but be careful with the signs

94. anonymous

I got this part let me draw it for you

95. anonymous

|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. anonymous

no thats not a negative its a minus

99. asnaseer

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

100. anonymous

ok

101. anonymous

6.76?

102. anonymous

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. anonymous

ok so 13.13

106. asnaseer

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

107. anonymous

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. anonymous

ok

110. asnaseer

yw :)

111. anonymous

Thanks once again!! :D

112. asnaseer

np :)

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