Answer:
[tex]x^2+4xy+4y^2[/tex]
Step-by-step explanation:
Multiply the exponent on the base out using the distributive property.
[tex](x+2y)^2\\(x+2y)(x+2y)\\x^2+2xy+2xy+4y^2\\x^2+4xy+4y^2[/tex]