Advanced MathMediumProduct of the outer coefficients
Advanced Math practice question
When (3x − 2)(x + 4) is written as ax² + bx + c, what is the value of a · c?
Answer: -24 or −24
Expanding gives 3x² + 10x − 8, so a = 3, c = −8, and ac = −24.
Common wrong answers
- If you answered 24
- 24 has the wrong sign; c is −8.
- If you answered 30
- 30 is a · b (3 × 10).
- If you answered -8
- −8 is c alone.
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