Factoring something with absolute value

In summary, to find the intersection of the equations y = |x| and 3y - x = 8, you must first equate the equations and then rewrite them to get rid of the absolute values. This can be done by writing two equations, one for x >= 0 and one for x < 0. The solutions for x are x = 4 and x = -4.
  • #1
zeion
466
1

Homework Statement



I need to find where these intersect:
y = |x|
3y - x = 8

Homework Equations





The Attempt at a Solution



I equate them:
|x| = (1/3)x + (8/3)
|x| - (1/3)x - (8/3) = 0
|3x| - x - 8 = 0
|2x| - 8 = 0
|x| = 4

Is that right?
How do I get the other solution?
 
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  • #2
zeion said:

Homework Statement



I need to find where these intersect:
y = |x|
3y - x = 8

Homework Equations





The Attempt at a Solution



I equate them:
|x| = (1/3)x + (8/3)
|x| - (1/3)x - (8/3) = 0
|3x| - x - 8 = 0
The line below is wrong. |3x| - x = 2x if x >=0, but is equal to -4x if x < 0.
Rewrite the line above as
|3x| = x + 8

Now get rid of the absolute values by writing two equations, one for x >= 0 and the other for x < 0. For example, if |a| = 2, then a = 2 or -a = 2.

Look at the section in your book that defines absolute values.

zeion said:
|2x| - 8 = 0
|x| = 4

Is that right?
How do I get the other solution?
 
  • #3
Are there some general rules I should know? About when to do a case?
 
  • #5
Okay great thank you I understand now
 

What is factoring with absolute value?

Factoring with absolute value is a mathematical process used to simplify expressions that contain absolute value symbols. Absolute value represents the distance of a number from zero on a number line and is always positive. Factoring with absolute value involves breaking down an expression into its factors, taking into account the absolute value of each factor.

When should I use factoring with absolute value?

Factoring with absolute value is typically used when simplifying algebraic expressions or solving equations. It can also be used to solve real-world problems involving distance or magnitude.

How do I factor an expression with absolute value?

To factor an expression with absolute value, first identify the absolute value symbols and rewrite the expression as a positive or negative value. Then, factor the expression as you would normally do, taking into account the absolute value sign. Finally, simplify the expression by removing the absolute value signs and considering both positive and negative solutions.

Can I factor out the absolute value symbol?

Yes, you can factor out the absolute value symbol if it is the only factor in an expression. For example, in the expression |x+3|, the absolute value symbol can be factored out, resulting in |x+3| = 1. This can be rewritten as x+3 = 1 or x+3 = -1, giving two possible solutions.

Are there any special rules for factoring with absolute value?

Yes, there are a few rules to keep in mind when factoring with absolute value. One rule is that the absolute value of a product is equal to the product of the absolute values. Another rule is that the absolute value of a sum is less than or equal to the sum of the absolute values. These rules can be useful when simplifying expressions involving multiple absolute value symbols.

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