Expand the expression $(2x + y + z)^2$.

1. Problem Description

Expand the expression $(2x + y + z)^2$.

2. Solution Steps

We want to expand $(2x + y + z)^2$.

We can use the formula for the square of a trinomial:

$(a + b + c)^2 = a^2 + b^2 + c^2 + 2ab + 2ac + 2bc$.

In this case, $a = 2x$, $b = y$, and $c = z$. Substituting these into the formula, we get:

$(2x + y + z)^2 = (2x)^2 + y^2 + z^2 + 2(2x)(y) + 2(2x)(z) + 2(y)(z)$

$= 4x^2 + y^2 + z^2 + 4xy + 4xz + 2yz$.

3. Final Answer

$4x^2 + y^2 + z^2 + 4xy + 4xz + 2yz$