P(c;d) = (2c^2+3c^2d+d) - ( 5c^4+3c^2d)
P(c;d) =(2c² +3c²d+d) -(5c⁴+3c²d) =2c² +3c²d+d -5c⁴-3c²d=2c² +d -5c⁴.