The identity (a − b)² is equal to:
Aa² − b²
Ba² − 2ab + b²
Ca² + 2ab + b²
Da² + ab − b²
Answer & Solution
Correct answer: B. a² − 2ab + b²
(a − b)² = (a − b)(a − b) = a² − ab − ba + b² = a² − 2ab + b². The middle term is negative, distinguishing this from (a + b)².