Write as an algebraic expression: *What is 21 less than double the square of a number?*

Flashcard 8 - Mathematics Flashcard Set for the PRAXIS Test

\[2x^{2}-21\]

The square of a number is \(x^{2}\).
Double that is \(2x^{2}\).
21 less than that is \(2x^{2}-21\).

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