Answer:
(a + b + c)(a + b - c)
Step-by-step explanation:
(a + b)² - c² ← is a difference of squares and factors in general as
x² - y² = (x + y)(x - y)
Here x = a + b and y = c , then
(a + b)² - c²
= (a + b + c)(a + b - c)
(a+b+c) (a+b-c)
