This can be written as (x+4)(x+4)
Multiply everything in the second parenthesis by the x.
x^2 + 4x
Multiply everything in the second parenthesis by 4.
4x + 16
Add these two equations together.
x^2 + 4x + 4x + 16
Combine like terms.
x^2 + 8x + 16
Hope this helps!
