Question

which of these are expressions?
check all that are true.
□ x + y
□ 9
□ x + 3 = 9
□ x + y = z
□ 3 + 9

Explanation:

An expression is a combination of numbers, variables, and operations without an equal sign (equations have equal signs).

• \( x + y \): Combines variables with addition, no equal sign → expression.
• \( 9 \): Single number, no equal sign → expression.
• \( x + 3 = 9 \): Has an equal sign (equation) → not an expression.
• \( x + y = z \): Has an equal sign (equation) → not an expression.
• \( 3 + 9 \): Combines numbers with addition, no equal sign → expression.

Answer:

• \( \boldsymbol{x + y} \)
• \( \boldsymbol{9} \)
• \( \boldsymbol{3 + 9} \)