Question Video: Identifying Using the Language of Algebra Mathematics

Identify whether 4𝑥 − 5𝑦 is an expression, an equation, an identity, a formula, or an inequality.

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Video Transcript

Identify whether four 𝑥 minus five 𝑦 is an expression, an equation, an identity, a formula, or an inequality.

Let’s take a look at what we have here: four 𝑥 minus five 𝑦. If we were answering an algebraic problem and we had this statement, four 𝑥 minus five 𝑦, we couldn’t do very much with this. We might be able to collect any like terms, but we couldn’t solve it. We can’t solve it because we’re missing something. We’re missing an equals sign. What we have here with four 𝑥 minus five 𝑦 is two separate terms linked by the subtraction. The word that we use for this is an expression.

If we look at an equation, we can remember that this needs an equals to symbol, and so do identities and formulas. So straightaway, we could say that four 𝑥 minus five 𝑦 is not an equation, an identity, or a formula. An inequality needs to have an inequality symbol, for example, less than or greater than or equal to. So four 𝑥 minus five 𝑦 is not an inequality. We can give our answer that four 𝑥 minus five 𝑦 is an expression.