Answer:
(a - b)(1 + a + b)
Step-by-step explanation:
Note that a² - b² is a difference of squares and factors as
a² - b² = (a - b)(a + b), thus
a - b + a² - b²
= a - b + (a - b)(a + b) ← factor out (a - b)
= (a - b)(1 + a + b)
