Упростите выражение: 4x(a+x+y)+4a(a-x-y)-4y(x-a-y).

\[4x(a + x + y) + 4a(a - x - y) - 4y\ \cdot\]

\[\cdot (x - a - y) = 4ax + 4x^{2} + 4xy + 4a^{2} -\]

\[- \ 4ax - 4ay - 4xy + 4ay + 4y^{2} =\]

\[= 4x² + 4a² + 4y².\]