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Advanced MathEasyLength of a rectangle from its area

Advanced Math practice question

The area of a rectangle is x² + 3x, and its width is x. Which expression gives its length?

  1. A. x + 3Correct
  2. B. x² + 3
  3. C. 3x
  4. D. x + 3x

Answer: A. x + 3

Area ÷ width: (x² + 3x)/x = x + 3.

Why the other answers are wrong

B. x² + 3
x² + 3 times x would be x³ + 3x.
C. 3x
3x times x is 3x², not x² + 3x.
D. x + 3x
x + 3x is 4x, and 4x times x is 4x².

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