If, for example, you had a problem looking something like this:
l3-4l= x
First you would completely forget that there is an absolute value sign. Just solve 3-4. You should get -1. Absolute value is just the distance on a number line something is from 0. Since -1 is 1 digit away from 0, the answer would be 1.
Another trick is to just solve the problem inside the absolute value sign. If you get a positive number, that's your answer. If you get a negative number, just take away the negative sign.
If you're solving equations or inequalities, then it can help to break it into two parts:
Absolute value of a variable u is: {u if u > 0}, {-u if u < 0}, so you can treat it as two different things to solve.
Example, say you have y > |x+2|, where the vertical bars are absolute value.
So you have y > x +2, when (x+2)>0, and you have y > -(x+2), when (x+2)<0. So first you need to find where (x+2)=0. This is at x = -2.
So you have {y > x + 2, when x > -2} and {y > -x - 2, when x < -2}. When x = 2, you can use either one, because they are both equal to zero.
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The definition of "absolute value" for a number x (written as |x| ) is:
|x| = x for x > 0
|x| = 0 for x = 0
|x| = -x for x < 0
... where x is replaced by some function - for example f(x):
|f(x)| = f(x) for f(x)>0
|f(x)| = 0 for f(x)=0
|f(x)| = -f(x) for f(x)<0
Often you can solve an equation to get the conditions where the sign changes. The answer above gives an example of this for the equation y > |x+2| which yields:
y > x+2 for x > -2
y > 0 for x = -2
y > -(x+2) for x < -2 ... or alternatively, -y < x+2 for x < -2
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Fractions make no difference to absolute values.
What's your question? To solve an absolute value inequality, knowledge of absolute values and solving inequalities are necessary. Absolute value inequalities can have one or two variables.
To solve equations with absolute values in them, square the absolute value and then take the square root. This works because the square of a negative number is positive, and the square root of that square is the abosolute value of the original number.
Additive opposites MUST have the same absolute values.
Absolute Value means the distance from 0, and so you should solve the equation with the number inside the Absolute Value lines as a positive and then solve again as a negative.