Here is an inequality: 3(10−2x)<18. The solution set for this inequality is all the values that can be used in place of x to make the inequality true. Each solution is one value that makes the inequality true.
In order to solve this inequality, we can first solve the related equation 3(10−2x)=18 to get the solution x=2. That means 2 is the boundary between values of x that make the inequality true and values that make the inequality false.
To solve the inequality, we can check numbers greater than 2 and less than 2 and see which ones make the inequality true.
Let’s check a number that is greater than 2: x=5. Replacing x with 5 in the inequality, we get 3(10−2⋅5)<18 or just 0<18. This is true, so x=5 is a solution. This means that all values greater than 2 make the inequality true. We can represent the solutions as x>2 and also represent the solutions on a number line:
Notice that 2 itself is not a solution because it's the value of x that makes 3(10−2x) equal to 18, and so it does not make 3(10−2x)<18 true.
For confirmation that we found the correct solution, we can also test a value that is less than 2. If we test x=0, we get 3(10−2⋅0)<18 or just 30<18. This is false, so x=0 and all values of x that are less than 2 are not solutions.