Solving Algebra Homework: 6+X = 3+(X/2)

[Saturnfirefly]

Homework Statement

6+X = 3+(X/2)
----
X

Homework Equations

Quadratic formula?

The Attempt at a Solution

2(6+X) = 3+X
------
X

12+2X = 3+X
------
X

12+2X = X(3+X)

12+2X = 3X-X^2

so,

X^2+X-12

when putting it in the quadratic formula, I don't get the right answers.
the answer should be X1= 2 X2= -6
what have I done wrong? :(

 

[TVP45]

You're messing up your operations. Go back to the first line in your attempt. The RHS is 3 + x/2 NOT (3 + x)/2

Try again

 

[Dick]

Starting with (X+6)/X=3+X/2, if you multiply both sides by 2 you get (2X+12)/X=6+X. Note the 6 instead of a 3. 3+X/2 is not the same as (3+X)/2.

 

[CaptainQuasar]

I haven't followed the whole thing through. But it looks like your first move is to multiply both sides by 2 and you got the wrong answer on the right side of the equation.

You wouldn't get 3+X, you'd get 2(3+X/2).

For the first step, you need to make a common denominator (2) on the right side before you multiply both sides by two. Does that make sense?

Or, do it Dick's way.

 

[Saturnfirefly]

Thank you very much! I got the right answer now. Am I supposed to grade the help I got? If so, how?

I'll probably have some more questions tonight... can I just post it in here or should I create a new thread?

 

[Dick]

Grades? Grade US? We don't need no steenking grades! :) If it's a new question start a new thread, old long threads tend to get overlooked.

 

[Saturnfirefly]

Oh, thought you were supposed to grade it as in some swedish forums :D.
Well, thank you again!

 

[TVP45]

If you want, give out ATTABOYs. When posters get 20 ATTABOYs, it cancels out one MY BAD!