Question

Sea P(x,y)=2x-3y; Q(x,y)=x+7y; R(x,y)=5x+y, calcula P(x,y)+Q(x,y)-R(x,y

Answer 1

P(x,y)+Q(x,y)-R(x,y)=H  (llamaremos H a la respuesta)
(2x-3y)+(x+7y)-(5x+y)=H
2x-3y+x+7y-5x-y=H
-2x-y=H