Respuesta :

Answer:

(5x + 7y)² = 25x² + 70xy + 49y²

Step-by-step explanation:

(5x + 7y)² = 25x² + 70xy + 49y²

Because,

(5x + b)² = (5x)² + 2(5x)(b) + b²

2(5x)(b) = 70xy

b = 7y

b² = (7y)² = 49y²