Algebra guide: make sense of the symbols
Understand expressions, substitution and simple equations, one idea at a time.
A little clearer.
A letter can stand for a number
Algebra uses symbols to represent values and relationships. A letter may stand for a number you do not yet know, or for a value that can change.
Start by reading an expression in words. For example, an expression with three lots of a value and an extra two tells you which operations are involved.
Substitution means using a given value
When you are given a value for a letter, replace the letter carefully and then calculate using the normal order of operations. Brackets are useful, especially when the value is negative.
An equation says two sides are equal
Solving a simple equation means finding a value that makes the statement true. Keep both sides balanced by applying the same operation to each side.
In the example below, subtract two from both sides, then divide both sides by three. Substitute the solution into the original equation to check it.
Build careful habits
Work one step at a time and keep equal statements on each line. If a step feels like a trick, ask what operation has actually been applied.
- Keep track of positive and negative signs.
- Use brackets when substituting a negative value.
- Check the answer in the original equation.
- Explain your method in words as well as symbols.
