Inequality with absolute values

In summary, when trying to determine the validity of the inequality |x+y| \leq |x| + |y|, it is helpful to consider two cases: when x and y have the same sign and when they have opposite signs. By working out each case, a proof can be obtained.
  • #1
DrunkenPhD
10
0
Wonder if this is true or just mistype:

|x+y| [itex]\leq[/itex] |x| +|y|

If this is true how to proof because cannot find it out anywhere written
Regards
 
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  • #2
wouldn't it be easy to demonstrate this by putting in numbers?
 
  • #3
DrunkenPhD said:
If this is true how to proof
Regards

What have you tried?
 
  • #4
pwsnafu said:
What have you tried?

Yes, please tell us what you tried.

Did you try plugging in some random numbers to check whether it works?
If it does always work, did you attempt a proof?
 
  • #5
DrunkenPhD said:
Wonder if this is true or just mistype:

|x+y| [itex]\leq[/itex] |x| +|y|

If this is true how to proof because cannot find it out anywhere written
Regards

There are basically two cases - x and y same sign, x and y opposite sign. Work out each case.
 

Related to Inequality with absolute values

1. What is "inequality with absolute values"?

Inequality with absolute values is a mathematical concept that deals with comparing two numbers or expressions that have absolute values, meaning they are always positive. Inequality with absolute values is often used to represent the distance between two numbers on a number line.

2. How do you solve an inequality with absolute values?

To solve an inequality with absolute values, you first isolate the absolute value expression on one side of the inequality. Then, you can rewrite the absolute value expression as two separate inequalities, one with a positive sign and one with a negative sign. Finally, solve each inequality separately to find the solution set.

3. What is the difference between solving an inequality with absolute values and solving a regular inequality?

The main difference between solving an inequality with absolute values and solving a regular inequality is that when dealing with absolute values, you must consider both the positive and negative values of the expression. This is because the absolute value of a number can be either positive or negative, depending on the value of the number itself.

4. Can you graph an inequality with absolute values?

Yes, you can graph an inequality with absolute values. The graph will show all the values that satisfy the inequality. To graph an inequality with absolute values, you can first graph the two separate inequalities that result from rewriting the absolute value expression, and then find the overlapping region between the two graphs.

5. What are some real-life applications of inequalities with absolute values?

Inequalities with absolute values are commonly used in data analysis, economics, and engineering. For example, in economics, absolute value inequalities can be used to represent the relationship between supply and demand. In engineering, they can be used to represent the tolerance of a manufactured part. They can also be used to model real-life situations that involve distance, such as calculating the maximum distance a car can travel on a given amount of gas.

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