Advanced MathMediumQuotient of a difference of cubes
Advanced Math practice question
For all x ≠ 2, (x³ − 8)/(x − 2) = x² + ax + b, where a and b are constants. What is the value of a + b?
Answer: 6
x³ − 8 = (x − 2)(x² + 2x + 4), so a = 2, b = 4 and a + b = 6.
Common wrong answers
- If you answered 2
- 2 is a alone.
- If you answered 4
- 4 is b alone.
- If you answered 8
- 8 uses b = 8 from the constant of x³ − 8.
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