Final answer:
An expression that contains at least two terms and is in simplest form is a mathematical expression with two or more parts that cannot be simplified any further.
Step-by-step explanation:
An expression that contains at least two terms and is in simplest form is a mathematical expression with two or more parts that cannot be simplified any further. It does not have any like terms or common factors between the terms.
For example, the expression 4x + 2y is in simplest form as it contains two terms (4x and 2y) that cannot be combined or simplified further.
Learn more about Simplifying mathematical expressions