$$4 { x }^{ 4 } y+3 { x }^{ 3 } +3y+5 { x }^{ 4 } y-5 { x }^{ 2 } +4y$$
$3x^{3}-5x^{2}+9yx^{4}+7y$
$x\left(9x+36yx^{2}-10\right)$
