Let's try the one answer with no remainder: (b² - 3b + 18)
If this is the answer, then, when multiplied by b+7, we should get
b³+4b²-3b+126
(b+7) (b² - 3b + 18) Distribute
= b³ - 3b² + 18b + 7b² - 21b + 126 Collect like terms
= b³ + 4b²-3b + 126
This number perfectly matches the numerator in the first term!
Therefore, the answer is D) b² − 3b + 18
