Inequalities are similar to equations, you have to solve for a variable (X, Y, Z , A, B, etc...), the main difference is that with an equation you are solving for only one value (X=3, Z=4, A=-9, etc) with an inequality you are solving for a range of numbers, that means that you variable can be a number greater than, less than, greater or equal than to, less or equal than to...
For Example: If X > 3 (X is greater than 3) , X can be any value from 3.1, 3.2, 5, 7, 900, 1000 and so on.
If you want to see this article as a video, please visit us at WWW.I-HATE-MATH.COM
Let's remember the symbols for inequalities
Greater than >
Less than < Greater than or equal to ≥ Less than or equal to ≤
We have the inequality 3(X-4) ≤ X - 6. Let's solve for "X" , that means to leave "X" alone. We can solve this like a regular equation.
First we need to remember PEMDAS (Please Excuse My Dear Aunt Sally). We have to solve for the parenthesis. Let's multiply 3 times X, and 3 times -4
Once we do the parenthesis, 3x - 12 ≤ X -6, let's move the "X" from the right to the left side, we do this by adding "X" to both sides.
Our inequality looks like this 2X - 12 ≤ X -6. Now we have to move -12 from the left to the right side, let's add 12 to both sides.
Our main goal is to leave "X" alone, 2 is multiplying X, let's eliminate him from the left side by dividing both sides by 2
Our result is X ≤ 3, that means that the value of X has to be a number less than or equal to the number 3. For example 3, 2, 1, 0 -1, -2, -3 and so on. We can also write our answer like this (-∞, 3], we use always parenthesis for the infinitive symbol , and we use a bracket because our inequality is less than or equal to. If our equation was 3(X-4) < X -6, then our answer would be ( -∞, 3) with a parenthesis, this means that X can not be 3, it has to be less than 3, for example 2.99, 2.50, 0, -1, -2, -3 . Conclusion. If you have an inequality with the equal symbol (≤≥) , you have to use the bracket [], if you have the inequality without the equal symbol (<>), then you have to use parenthesis ()
Check our other articles about how to solve equations if you are having trouble solving for "X" Understand the inequality symbols If you divide by a negative number both sides, your inequality symbol will flip to the opposite side. For Example: -3X>6, -3X/-3 > 6/ -3, then X<-2, if you have doubts, just plug your answer and make sure makes sense, in our example X has to be less than -2 , so -3(-3) > 6, 9> 6, if you do not flip the inequality then your answer would be wrong.
