Final answer:
A mathematical expression is a combination of variables, numbers, and operations. It represents a relationship or a calculation. The variables in an expression can take on different values, allowing for flexibility in solving equations and representing relationships in mathematics.
Step-by-step explanation:
A mathematical expression is a combination of variables, numbers, and operations. It represents a relationship or a calculation. For example, the expression 3x + 2y - 5 represents the sum of three times x, two times y, and negative five. Each term in the expression must have the same dimensions. The variables in an expression can take on different values, which allows for flexibility in solving equations and representing relationships in mathematics.