thiss question too - mathss

  • 3 votes

(3x+1)/4 =( (4x-1)/8 ) +2

guyss this is a similar sort of question and for this i got x=-1/2

just want to double chek with u guuys =)

Posted Sun 5th June, 2011 @ 12:57 by Anam

19 Answers

  • 4 votes

it has to be 6.5

method 1

(3x+1)/4=((4x-1)/8)+2

8(3x+1)=4(4x-1) +2x8x4

24x+8=16x - 4+64

8x=-4+64-8

8x=52

x=6.5

Answered Sun 5th June, 2011 @ 13:14 by Pui Pui
  • 3 votes

@Anam, i've got the same answer as you now but with the way i did it :)

@Pui Pui, thanks - that makes more sense. what did you do to get 6.5?

Answered Sun 5th June, 2011 @ 13:10 by Kelly:)
  • 3 votes

I also got x=6.5    

(because you can't factorise unless the products are multiples of each other)

(3x+1)/4 = ( (4x-1)/8 ) +2

(3x+1)/4 - (4x-1)/8 = 2

(2x+3)/8 = 2

2x+3 = 8*2

2x+3 = 16

2x = 13

x = 13/2

x = 6.5

Hope this helps!

Answered Sun 5th June, 2011 @ 13:51 by Becca
  • 3 votes

oh I get it now :) thanks guys!

Answered Sun 5th June, 2011 @ 15:05 by Kelly:)
  • 2 votes

ermmm... i got 6.5

Answered Sun 5th June, 2011 @ 13:07 by Pui Pui
  • 2 votes

or alternatively

(3x+1)/4   - (4x-1)/8 = 2

2(3x+1)/8 - (4x-1)/8 = 2     (common denominator)

(6x+2-4x+1)/8=2

6x+2-4x+1=16

2x+3=16

2x=13

x=6.5

Answered Sun 5th June, 2011 @ 13:17 by Pui Pui
  • 1 vote

i got -1.25 :S

Answered Sun 5th June, 2011 @ 12:59 by Kelly:)
  • 1 vote

ermm okayy..

wat i did was times both the sides by their common multiple of the denominators which in this case is 8.

when i did this i was left with

2(3x+1) = 1 (4x-1+2)

i expandad this normalyy and worked out to be x= -1/2

Answered Sun 5th June, 2011 @ 13:04 by Anam
  • 1 vote

oh right

i just multiplied the sides by the denominator on the other side so:

8(3x + 1) = 4(4x-1) +2 and worked it out from there. :S

your way makes sense as well but i really don't know :S

Answered Sun 5th June, 2011 @ 13:07 by Kelly:)
  • 1 vote

@kelly:) yeahh when u times the denominator on both sides the four and the three would be divided by them so when u times the first side by 8. it would be 8/4 which is 2

Answered Sun 5th June, 2011 @ 13:12 by Anam
  • 1 vote

i don't understand why you're multiplying the 2 on the right by both 8 and 4 :S

Answered Sun 5th June, 2011 @ 13:19 by Kelly:)
  • 1 vote

(3x+1) the whole thing divided by 4 = (4x-1) divided by 8 and then plus 2

so...

when u times both sides by 8, the denominators would go, becoming 2(3x+1) = 1 (4x-1+2)

this is:

6x +2 = 4x -1 +2

6x-4x = -1 +2 -2

2x = -1

x = -1/2

hope thiss makes more sense and please correct me if im wrong

Answered Sun 5th June, 2011 @ 13:21 by Anam
  • 1 vote

because its +2 its a different term so whatever you do to the other terms you have to do the same to it

Answered Sun 5th June, 2011 @ 13:22 by Pui Pui
Edited by Pui Pui on Sun 5th June, 2011 @ 15:14
  • 1 vote

i got the exact same as you Anam i just did it a different way :)

Answered Sun 5th June, 2011 @ 13:23 by Kelly:)
  • 1 vote

if you times both sides by 8 your only making a difference to the top not the bottom because

eg. (3x+1)/8  x   8   is actually (3x+1)/8    x 8/1

so it would be (24x +8)/8

Answered Sun 5th June, 2011 @ 13:28 by Pui Pui
  • 1 vote

http://getrevising.co.uk/resources/answer_to_maths_question_posted_by_anam

heres a link to a word document i created to answer the question i hope u understand after reading it

Answered Sun 5th June, 2011 @ 13:49 by Pui Pui
  • 1 vote

yeah thats one of the ways i worked it out too

@anam and @kelly:)  I think you don't quite understand that whatever you do to one term you have to do to another so that the equation stays the same

Answered Sun 5th June, 2011 @ 14:56 by Pui Pui
  • 1 vote

I keep trying different ways but never get to 6.5! I got 7.5 though.
When I took the 2nd fraction over though I ended up with (2x + 1)/8 = 2 rather than + 3 because it's 6x + 2 - 4x - 1 meaning it goes to 2x + 1 surely? 2 - 1 = 1??

Answered Sun 5th June, 2011 @ 15:02 by Kelly:)
  • 0 votes

yeah but you have to times the 2 by 8 and 4

Answered Sun 5th June, 2011 @ 13:08 by Pui Pui