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some equation help please

ok i got

3x = -1/3x + 3

the answer has x = 0.9

and i agree as 2.7 = -0.3 + 3

but

when i try to solve it

i get

3x + 1/3x = 3

10/3x = 3

what do i do from here? im confused :/
Reply 1
Avatar for 04ayasin
04ayasin
3x + 1/3x = 3
But how do you get 10/3x = 3
That is wrong.
Try to get rid of the fraction by multiplying by something
Reply 2
Avatar for TimetoSucceed
TimetoSucceed
OP
7
because that basically gives 3.3x = 3

so x = 1.1, which is wrong
Reply 3
Avatar for TimetoSucceed
TimetoSucceed
OP
7
Original post by 04ayasin
3x + 1/3x = 3
But how do you get 10/3x = 3
That is wrong.
Try to get rid of the fraction by multiplying by something


isnt 3x the same as 9/3x? + 1/3x = 10/3x?
3x = -1/3x + 3

Multiply the whole equation by x

it becomes 3x^2 = -1/3 + 3x

Rearrange

3x^2 -3x + 1/3 = 0

then by quadratic formula

x = (3 +/- (9 - 4(3)(1/3))^1/2) / 6

x=1/2 + ((5)^1/2)/6 OR x=1/2 - ((5)^1/2)/6
Original post by TimetoSucceed

10/3x = 3



Fine so far.

Then, multiply both sides by 3, and divide both sides by 10.

Your notation is somewhat ambiguous, as 1/3x, could mean (1/3)x or 1/(3x). And from your desired answer I'm asuming it's the first one.
(edited 12 years ago)
How to write math equations in this forum?
Original post by ReviseRevise123
3x = -1/3x + 3

Multiply the whole equation by x

it becomes 3x^2 = -1/3 + 3x

Rearrange

3x^2 -3x + 1/3 = 0

then by quadratic formula

x = (3 +/- (9 - 4(3)(1/3))^1/2) / 6

x=1/2 + ((5)^1/2)/6 OR x=1/2 - ((5)^1/2)/6



x=1/2 + ((5)^1/2)/6 (which is approximately 0.9 in 1 decimal place)
Original post by ReviseRevise123
How to write math equations in this forum?


See the reference to LaTex at the top of this thread, and at the top of the forum.
Reply 9
Avatar for TimetoSucceed
TimetoSucceed
OP
7
ah yeah thanks =]
Original post by ghostwalker
See the reference to LaTex at the top of this thread, and at the top of the forum.


Cool.

Let me practice it on this thread.

3x=3x = −13x\frac{-1}{3x}+3+3

1. Multiply both sides by x and rearrange so it equates to zero.

3x23x^2 −3x-3x+13=0+\frac{1}{3}=0

2. Solve by quadratic formula

a= 3, b= -3, c= 1/3

x=−(−3)±32−4(3)(1/3)2(3)x = \frac{-(-3) \pm \sqrt{3^2-4(3)(1/3)}}{2(3)}

and you should get:

x=0.8726779962x = 0.8726779962

which is approximately x=0.9 x=0.9 (1 d.p.) :wink:
Reply 11
Avatar for 04ayasin
04ayasin
Original post by TimetoSucceed
isnt 3x the same as 9/3x? + 1/3x = 10/3x?


sorry i thought you meant 10/(3x) not (10/3)x Looks like I need to read that thing telling you how to set ut equations on this site.

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