Absolute value on both side of equation

In summary, the conversation discusses solving an absolute value equation and the answer given in the book, which states that x can be greater than or equal to 0 or equal to -2/3. The method for solving such equations is to consider two separate cases: when (3x+2) is not equal to 0 and when it is equal to 0, resulting in the solutions x=0 and x=-2/3 respectively.
  • #1
ziaharipur
6
0
I solved this absolute value equation and I am confuse about the answer given in the book for this question, the answer in the book is x > = 0 or x = -2/3 please tell me how can I get this answer from the following solution. Please tell the method which should be true for all such type of questions.
look at the image below
[PLAIN]http://img261.imageshack.us/img261/1577/imgsb.jpg
 
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  • #2
ok well... one of the mistakes I see is how you reached the conclusion "3x +2 =3x +2 for all real nobs"

well, this isn't true... is it? ex: x= -1. |3(-1)+2(-1)| does not equal (-1)|3(-1)+2|.

Break it up like this:
{[tex] |3x^2 + 2x|= |x||3x+2| = x |3x + 2| [/tex] } [tex] \Rightarrow [/tex] { [tex] |x|=x , for (3x+2) \neq 0 [/tex] }

Hence, this is true for all [tex] x \geq 0[/tex].

Now, separately consider the case (3x+2)=0. What do you get? x= -2/3

Note: LaTeX is being crazy!
 
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1. What is the absolute value of a number?

The absolute value of a number is the distance of that number from 0 on the number line. It is always positive and represented by vertical bars surrounding the number.

2. Can you give an example of an equation with absolute value on both sides?

One example is |x + 2| = |3x + 1|

3. How do you solve an equation with absolute value on both sides?

To solve an equation with absolute value on both sides, you need to split the equation into two separate equations, one with a positive and one with a negative absolute value. Then you solve each equation separately to find the possible values for the variable.

4. Why do we use absolute value on both sides in equations?

We use absolute value on both sides in equations to ensure that all possible solutions are accounted for. This is because absolute value represents the distance from 0, so there can be multiple solutions for a single equation.

5. Can an equation with absolute value on both sides have no solution?

Yes, an equation with absolute value on both sides can have no solution if the two equations after splitting do not have any common solutions. This can happen if the absolute values have different signs.

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