Advanced Math practice question

Answer: 11

Square both sides to undo the square root: x + 5 = 16. Then x = 11. Always check: √(11 + 5) = √16 = 4. ✓

Common wrong answers

If you answered 16

You squared both sides correctly to get x + 5 = 16, but stopped there — subtract 5 to get x = 11.

If you answered 21

You squared correctly to get x + 5 = 16 but then added 5 instead of subtracting it; x = 16 − 5 = 11.

If you answered -1

You subtracted 5 from 4 instead of undoing the square root first. Square both sides: x + 5 = 16, so x = 11.

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