(A)
(x⁴ + x³ + 7x² - 6x + 8) ÷ (x² + 2x + 8)
x² - x + 1
x² + 2x + 8 ) x⁴ + x³ + 7x² - 6x + 8
- x⁴ + 2x³ + 8x²
-x³ - x² - 6x
- -x³ - 2x² - 8x
x² + 2x + 8
- x² + 2x + 8
0
Answer: x² - x + 1
(B) Distribution Method
(x² - x + 1)(x² + 2x + 8)
= x²(x² + 2x + 8) - x(x² + 2x + 8) + 1(x² + 2x + 8)
= x⁴ + 2x³ + 8x² - x³ - 2x² - 8x + x² + 2x + 8
= x⁴ + (2x³ - x³) + (8x² - 2x² + x²) + (-8x + 2x) + 8
= x⁴ + x³ + 7x² - 6x + 8