(x+4)^2 how do i do it?

(x+4)(x+4)

FOIL

x^2 + 4x + 4x + 4^2

=x^2 + 8x + 16

(x + 4)(x + 4)
x² + 4x + 4x + 16
x² + 8x + 16

(x+4)²=(x+4)(x+4)

=x(x+4)+4(x+4)

=x²+4x+4x+16

=x²+8x+16

You can also use the formula (a+b)²=a²+2ab+b²
where in we have a=x and b=4

(x+4)²=x²+2(x)(4)+4²

=x²+8x+16

this has the formula
(a+b)²
=a²+2ab+b²
in this context (x+4)²
= x² + 2(x)(4)+ 4²
= x² + 8x + 16

(x + 4)^2
= (x + 4)(x + 4)
= x^2 + 4x + 4x + 16
= x^2 + 8x + 16

Raul is right.
It goes (x+4)^2 = (x+4)(x+4)
Then one can expand these brackets by multiplying the first two terms of each bracket together [x*x=x^2 ]
Then multiply the first term of the first bracket with the second term of the second bracket [x*4 = 4x]. Next multiply the first term of the second bracket with the second term of the first bracket [x*4= 4x] and finally the last terms of each bracket [4*4 = 16].
Putting all this together one gets;
x^2+4x+4x+16
which can be simplified to x^2+8x+16
That simple. The FOIL that Raul mentioned refers to the expansion process, abbreviated from First, Outside, Inside, Last (i.e. multiply the first two terms together, then the outside term, inside term and lastly the last term)

yes it is not, there is a general rule
(x+4)^2 = x^2+2*x*4+16

You would have to FOIL it. FOIL = First, Outside, Inside, Last.

(x+4)(x+4) =
x^2 + 4x + 4x + 16 =
x^2 + 8x + 16.

how did you get x^2+16

x^2+8x+16