Advanced MathHardx³ coefficient in a quadratic product
Advanced Math practice question
When (x² + 3x)(x² − x + 5) is expanded, what is the coefficient of x³?
Answer: 2
x³ arises from x² · (−x) and 3x · x²: −1 + 3 = 2.
Common wrong answers
- If you answered 3
- 3 counts only the 3x · x² product; combine it with x² · (−x) = −x³ to get 2x³.
- If you answered 4
- Only two products land on x³: −1 + 3 = 2.
- If you answered -1
- −x³ from x² · (−x) must be combined with +3x³ from 3x · x².
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