Answer:
x^2 + 8x + 16
Explanation:
x^y
an exponent is the the value of x, multiplied by x, for y times.
so, (x+4)^2 is the same as (x+4)*(x+4). Then you just simplify using FOIL.
F-first x*x = x^2
O-outer x*4 = 4x
I-inner 4*x = 4x
L-last 4*4 = 16
Now, you've got your quadratic equation. x^2 + 8x (because 4x+4x=8x) + 16