bjr

1 - cours distributivité : k (a+b) = k*a + k*b

x 12 = x (10 + 2)

donc 7,89 x 12 = 7,89 x 10 + 7,89 x 2 = 78,90 + 15,78 = 94,68

10,37 x 18 = 10,37 x (20 - 2) = 10,37 x 20 - 10,37 x 2 = 186,66

45,6 x 128 = 45,6 x (100 + 30 - 2) = 45,60x100 +45,60x30-45,60x2= 5836,80

0,934 x 137 - 0,934 x 37 = 0,934 x 100 = 93,40

516 x 0,73 + 0,27 x 516 = 516 (0,73+0,27) = 516

1,618 x 37 - 1,618 x 11 - 1,618 x 6 = 1,618 x (37 - 11 - 6 ) =32,36

7 (2a + 11) = 7*2a + 7*11 = 14a + 77

2x (8-5x) = 2x*8 + 2x*(-5x) = -10x² + 16x

3a (2b+7-c) = 6ab + 21a - 3ac

20 - 35t = 4x5 - 7x5t = 5 (4-7t)

6r + 9r² = 3x2xr + 3x3xrxr = 3r (2 + 3r)

16g - g ² + 3gh = g(16 - g + 3h)

7x0,95 + 7x0,80 ou 7 (0,95 + 0,80)