A = 12x²-10x-48x+40 - (49x²-126x+81)
= 12x² -58x+40+49x²+126x-81
= 61x²+68x -41
pour x = -3
A = 61*-3² +68*-3-41
= 61*9-204-41
= 549-245 = 304
pour x = 5/6
A = 61*(5/6)²+68*5/6-41
= 61*25/36+340/6-41
= 1525/36 +2040/36-1476/36
= 2089/36
pour x = 1/3
A = 61*(1/3)² +68*1/3-41
= 61*1/9+68/3-41
= 61/9 + 204/9-369/9
= 104/9
