# Write and solve inequalities

And that works well for adding and subtracting, because if we add or subtract the same amount from both sides, it does not affect the inequality Example: Writing inequalities algebra Absolute value inequalities Video transcript A carpenter is using a lathe to shape the final leg of a hand-crafted table. A lathe is this carpentry tool that spins things around, and so it can be used to make things that are, I guess you could say, almost cylindrical in shape, like a leg for a table or something like that.

In order for the leg to fit, it needs to be millimeters wide, allowing for a margin of error of 2.

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Now, they want us to write an absolute value inequality that models this relationship, and then find the range of widths that the table leg can be. So the way to think about this, let's let w be the width of the table leg. So if we were to take the difference between w andwhat is this? This is essentially how much of an error did we make, right?

Write and solve inequalities w is going to be larger thanlet's say it'sthen this difference is going to be 1 millimeter, we were over by 1 millimeter. If w is less thanit's going to be a negative number.

If, say, w wasminus is going to be negative 1. But we just care about the absolute margin. So we just really care about the absolute value of the difference between w and This tells us, how much of an error did we make?

And all we care is that error, that absolute error, has to be a less than 2.

## Solving inequalities | Algebra I | Math | Khan Academy

And I'm assuming less than-- they're saying a margin of error of 2. So this is the first part. We have written an absolute value inequality that models this relationship. And I really want you to understand this. All we're saying is look, this right here is the difference between the actual width of our leg and Now we don't care if it's above or below, we just care about the absolute distance fromor the absolute value of that difference, so we took the absolute value.

Now, we've seen examples of solving this before. So let me write this down. So this means that w minus has to be less than 2.

## Writing and Solving Inequalities

So let's solve each of these. If we add to both sides of these equations, if you add and we can actually do both of them simultaneously-- let's add on this side, too, what do we get? What do we get? The left-hand side of this equation just becomes a w-- these cancel out-- is less than or equal to plus 2.

And on this side of the equation-- this cancels out-- we just have a w is greater than or equal to negative 2. So the width of our leg has to be greater than We can write it like this. The width has to be less than or equal to Or it has to be greater than or equal to, or we could say And that's the range.Understand solving an equation or inequality as a process of answering a question: which values from a specified set, if any, make the equation or inequality true?

Use substitution to determine whether a given number in a specified set makes an equation or inequality true. B) Have students write each of the following inequalities one at a time as you give them. Have them guess a reasonable solution and write their guess. Then ask them to replace the inequality symbol with an equal sign and solve the equation using inverse operations.

Learn how to solve compound inequalities.

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For example, solve 2x+1>3 AND -x-5Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere. In this lesson you will learn to create an inequality given a word problem by using algebraic reasoning. After we’ve mastered how to solve Absolute Value Inequalities, we are going to learn how to write an equation or inequality involving absolute value to describe a graph or statement.

Now, when solving Absolute Value Inequalities, we must never lose sight of . Introduction to Inequalities. Inequality tells us about the relative size of two values. We can write that down like this: b > a (Where "b" means how fast Billy was, ">" means "greater than", and "a" means how fast Alex was) Less Than or Greater Than Comparing Numbers Solving Inequalities Properties of Inequalities Solving Inequality.

Writing, Solving, and Graphing Inequalities in One Variable