Advanced MathEasy–MediumMiddle coefficient of a rectangle's area
Advanced Math practice question
A rectangle has length 2x + 3 and width x − 1. Its area can be written as 2x² + bx − 3, where b is a constant. What is the value of b?
Answer: 1
(2x + 3)(x − 1) = 2x² − 2x + 3x − 3 = 2x² + x − 3, so b = 1.
Common wrong answers
- If you answered 3
- 3 keeps only the +3x term.
- If you answered 5
- 5 adds 2 and 3 instead of combining −2x and 3x.
- If you answered -1
- −1 has the sign of the middle term wrong.
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