$${ \left(x+5y \right) }^{ 7 }$$
$x^{7}+21875x^{3}y^{4}+65625x^{2}y^{5}+109375xy^{6}+78125y^{7}+4375y^{3}x^{4}+525y^{2}x^{5}+35yx^{6}$
$\left(x+5y\right)^{7}$
