Answer:
The answer is a² + 2ab + b² - c²
Step-by-step explanation:
(a + b + c) × (a + b - c)
a² + ab - ac + ba + b² - bc + ca + cb - c²
a² + ab + ba - ac + ca + b² - bc + cb - c²
a² + 2ab + b² - c²
Thus, The answer is a² + 2ab + b² - c²
<u>-TheUnknownScientist</u><u> 72</u>