Posted by Lily on Wednesday, June 11, 2008 at 4:47pm.
the problem is that I have to find the length of x.
Here's what they say:
Find the missing length, when the perimeter is 9x+11
then here are the length that are given on the shape: 2x+3 and 3x+1
How could I solve this?

Pre Algebra  bobpursley, Wednesday, June 11, 2008 at 4:55pm
Three sides: add them to get perimeter.
x + 2x+3 + 3x+1= 9x+11
solve for x.

Pre Algebra  Lily, Wednesday, June 11, 2008 at 5:10pm
But the problem is about adding and subtracting polynomials...
This is what I did...
2x+3+3x+1
=2x+3x+3+1
=5x+4
and
9x+115x+4
=9x5x+11+4
=4x+15
but then, if I add both 5x+4+4x+15
=9x+19...

Pre Algebra  Amy, Wednesday, June 11, 2008 at 5:40pm
BobPursely gave this equation:
x + 2x+3 + 3x+1= 9x+11
If you only look at the left side, you'll get 6x + 4.
Your new equation should read:
6x + 4 = 9x + 11
Does that help?

Pre Algebra  Lily, Wednesday, June 11, 2008 at 5:54pm
im not sure?

Pre Algebra  Amy, Wednesday, June 11, 2008 at 5:56pm
Ok. From here, you need to solve for x. The easiest way to do that is to get x on one side of the equation. Do you know how to do that?

Pre Algebra  Lily, Wednesday, June 11, 2008 at 6:00pm
yes :)
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