Simplifying algebraic expressions
In a nutshell
Algebraic terms which have the same letter are called 'like terms'. Like terms can be added or subtracted, e.g. 2x+3x=5x. This is called simplifying. If terms have different letters, they cannot be simplified, e.g. 5x+3y. Take care with + or −signs. The − belongs to the term it is in front of.
Example
In the expression 2x−7t, the − belongs to 7t.
Simplifying expressions
Terms with different powers cannot be added or subtracted..
Examples
5a+10b−2a−3b 3x2+2x 3x2+2x−x2+7x 4xy+3x+xy=3a+7b=3x2+2x=2x2+9x=3x+5xy
Note: 3x2+2x cannot be simplified.
It is possible to use expressions to help you solve geometric problems.
Example 1
Write an expression for the perimeter of the following shape.
Perimeter =2m+2n
Example 2
Write an expression for the perimeter of the following shape. Simplify your answer as much as possible.
Perimeter =x+y+x+y+3x−y
Perimeter =5x+2y