What is a mathematical sentence that shows that two expressions are equivelent?

Answer 1

That one mathematical expression implies another is written as an arrowhead pointing to what it implies. The symbol with an arrowhead at both ends means each implies the other, so they are equivalent. In words, each is sufficient and necessary, is often used, although I prefer the double arrow.

Answer 2

A mathematical sentence that shows two expressions are equivalent is often represented using the equality symbol "=". For example, the equation (2(x + 3) = 2x + 6) illustrates that the expression on the left is equivalent to the expression on the right. This means that for any value of (x), both sides of the equation yield the same result.