Solve.

l 2x +1 l = 4

I've never done 'exact; values before any help would be awsome. i've got 3/2 and -5/2, or is it 5/2?

Thanks.

Printable View

- Feb 4th 2008, 04:22 PMwhite_capQuick easy question.
Solve.

l 2x +1 l = 4

I've never done 'exact; values before any help would be awsome. i've got 3/2 and -5/2, or is it 5/2?

Thanks. - Feb 4th 2008, 05:14 PMCursed
Well, your original answers of $\displaystyle {\frac{3}{2}}$ and $\displaystyle -{\frac{5}{2}}$ are correct.

Basically you have to solve the equation twice. The first time you treat the absolute value as if it were positive, and the second time you treat the absolute value as if it were negative. You do this so you can figure out the positive and negative values that work.

$\displaystyle (2x+1)=4$ and $\displaystyle -(2x+1)=4

$

You can always check your answers by plugging them in:

$\displaystyle | 2({\frac{3}{2}}) + 1 | = 4$

$\displaystyle |4| = 4.$ Correct.

--------------

$\displaystyle | 2(-{\frac{5}{2}}) + 1 | = 4$

$\displaystyle |-4| = 4.$ Correct.

--------------

$\displaystyle | 2({\frac{5}{2}}) + 1 | = 4$

$\displaystyle |6| = 4.$ Wrong. - Feb 7th 2008, 09:39 AMpombiux4
- Feb 18th 2009, 12:09 PMmr fantastic