Solving inequalities

Solve a linear inequality, and learn the one rule that is different from an equation. About 8 minutes, GCSE.

What you will do

1. A range, not a number. An inequality like x < 6 says x can be any number below 6. We solve it with the same balancing moves as an equation, with one exception.
2. The balancing moves. Add, subtract, multiply or divide by a positive number on both sides, and the sign stays the same.
3. The one special rule. Multiply or divide by a negative number and you must flip the sign. Try it with -2 < 3: multiply by -1 and you get 2 < -3, which is false, so it has to become 2 > -3.
4. Unknowns on both sides. Collect the x terms on one side first. Then watch for a negative coefficient.
5. Test your answer. Check by trying a value inside the answer and one outside in the original inequality.