(7,3c-c^2+4)+0,5c^2-(8,7c-2,4c^2)

(7,3c-c^2+4)+0,5c^2-(8,7c-2,4c^2) = 7,3c-c^2+4+0,5c^2-8,7c+2,4c^2 = -1.4c-c^2+4+0.5c^2+2.4c^2 = -1.4c+1.9c^2+4