bsr,calculer les produits proposés sans poser de multiplication: a) 36 x 19; b) 44 x 29; c) 35 x 99.

bonsoir

36x19 = 36 x (20-1) = 720 -36 = 684

44 x 29 = (40+4)(20+9) =800 +360 +80 +36 = 1160+80+36 =1240+36= 1276

35 x99 = 35 x( 100 -1) = 3500 -35 = 3465

a) 36 * 19 = 
(40 - 4) (20 - 1) = 
40 * 20 + 40 * (- 1) - 4 * 20 - 4 * (- 1) = 
800 - 40 - 80 + 4 = 
684

b) 44 * 29 = 
(40 + 4) (30 - 1) = 
40 * 30 + 40 * (- 1) + 4 * 30 + 4 * (- 1) = 
1 200 - 40 + 120 - 4 = 
1 276

c) 35 * 99 = 
35 * (100 - 1) = 
35 * 100 + 35 * (- 1) = 
3 500 - 35 = 
3 465