Advanced Math practice question

Answer: A. 3√2

Simplify each root: √72 = √(36 · 2) = 6√2 and √18 = √(9 · 2) = 3√2. Then 6√2 − 3√2 = 3√2.

Why the other answers are wrong

B. √54

√54 subtracts the numbers under the roots (72 − 18). Roots don't combine that way; simplify each first.

C. 9√2

9√2 ADDS 6√2 and 3√2. The expression subtracts.

D. 3√6

3√6 mixes up the simplified forms; √72 = 6√2, not 6√6.

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