Question

which of these are equations? select all that apply.
2r + 20
2 + 20r
\frac{20}{2} + r
2r = 20

Explanation:

Step1: Recall the definition of an equation

An equation is a mathematical statement that shows the equality of two expressions, meaning it contains an equal sign ($=$).

Step2: Analyze each option

• For \(2r + 20\): This is an algebraic expression, not an equation (no equal sign).
• For \(2 + 20r\): This is an algebraic expression, not an equation (no equal sign).
• For \(\frac{20}{2}+r\): This is an algebraic expression, not an equation (no equal sign).
• For \(2r = 20\): This contains an equal sign, showing that the expression \(2r\) is equal to \(20\), so it is an equation.

Answer:

\(2r = 20\)