Advanced MathEasyProduct of conjugate binomials
Advanced Math practice question
Which expression is equivalent to (x − 7)(x + 7)?
- A. x² − 49Correct
- B. x² + 49
- C. x² − 14x − 49
- D. x² − 14
Answer: A. x² − 49
(x − 7)(x + 7) = x² + 7x − 7x − 49 = x² − 49. The middle terms cancel.
Why the other answers are wrong
- B. x² + 49
- The constant is −7 × 7 = −49, not +49.
- C. x² − 14x − 49
- The x terms +7x and −7x cancel; there is no −14x.
- D. x² − 14
- 7 × 7 = 49, not 14.
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