Advanced MathMediumRecognising a difference of squares product
Advanced Math practice question
A square tile has side length 3x + 1 units, and a rectangular tile has sides of 3x + 1 and 3x − 1 units. Which expression gives the area of the rectangular tile?
- A. 9x² − 1Correct
- B. 9x² + 1
- C. 9x² − 6x + 1
- D. 6x
Answer: A. 9x² − 1
(3x + 1)(3x − 1) is a difference of squares: (3x)² − 1² = 9x² − 1.
Why the other answers are wrong
- B. 9x² + 1
- 9x² + 1 has the wrong sign on the constant.
- C. 9x² − 6x + 1
- 9x² − 6x + 1 is (3x − 1)², a square, not this product.
- D. 6x
- 6x is the SUM of the two sides, not the product.
More Advanced Math questions
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If √(x + 5) = 4, what is the value of x? - Medium
If f(x) = x + 3 and g(x) = 2x, what is f(g(4))? - Medium
What are the solutions to x² + 6x + 8 = 0?
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