(5x + y^5)^2 = (5x + y^5)(5x + y^5)
Expanding using the distributive property:
= 25x^2 + 5xy^5 + 5xy^5 + y^10
= 25x^2 + 10xy^5 + y^10

So, (5x + y^5)^2 = 25x^2 + 10xy^5 + y^10