Respuesta :

Answer:

20

Step-by-step explanation:

note that

(a - b)² = a² + b² - 2ab , thus

a² + b² - 2ab = (a - b)² ( add 2ab to both sides )

a² + b² = (a - b)² + 2ab = 4² + 2(2) = 16 + 4 = 20