Most mathematical expressions can be represented in different, but mathematically equivalent forms. Some of these forms might look simpler; for example, they can be visibly shorter. However, there is no universal idea as to which form of an expression is simplest. The form of a mathematical expression that is simplest for one problem turns out to be complicated or even unsuitable for another problem.
If the problem you want to solve requires a particular form
of an expression (expanded, factored, or expressed in particular terms),
choose the appropriate simplification function. If you do not need
a particular form of an expression, use
You also can substitute for any part of an expression with a
new value by using