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Example

Simplifying (2)2(\sqrt{2})^2 and (11)2(-\sqrt{11})^2

Simplify two expressions in which a square root is raised to the second power, demonstrating that squaring undoes the square root.

(2)2(\sqrt{2})^2:

Rewrite the squared expression as a product of two identical factors:

(2)2=(2)(2)(\sqrt{2})^2 = (\sqrt{2})(\sqrt{2})

Apply the Product Property to combine the two radicals:

(2)(2)=4=2(\sqrt{2})(\sqrt{2}) = \sqrt{4} = 2

The result is 2 — squaring a square root returns the original radicand.

(11)2(-\sqrt{11})^2:

Rewrite as a product of two identical factors:

(11)2=(11)(11)(-\sqrt{11})^2 = (-\sqrt{11})(-\sqrt{11})

Multiplying two negative quantities gives a positive result. Combine the radicals:

(11)(11)=121=11(-\sqrt{11})(-\sqrt{11}) = \sqrt{121} = 11

The result is 11. The negative signs cancel because the product of two negatives is positive, and then 1111=121=11\sqrt{11} \cdot \sqrt{11} = \sqrt{121} = 11. In general, (a)2=a(\sqrt{a})^2 = a for any nonnegative number aa, and (a)2=a(-\sqrt{a})^2 = a as well, since squaring eliminates the negative sign.

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Updated 2026-04-21

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