1&2 svp je n'y arrive pas :o URGENT 4Eme

Ex 1:

a) -7/50 + 2/75 = -21/150 + 4/150 = 17/150

b) 1/5 + -2/3 = 3/15 + -10/15 = -7/15

c) 1/12 - 1/9 = 3/36 - 4/36 = -1/36

d) 17/-24 + (-5/36) = 102/-144 + (-20/144) = -122/144 = 61x2/ 72x2= 61/72

e) 3/16 - -1/12 = 9/48 + 4/48 = 13/48

f) 8/-17 - (-1/15) = 120/-255 - (-17/255) = -103/255

Ex 2:

a) -7/25 x -5/8 = -7/5x5 x 5x-1/8 = 7/40

b) 18/-49 x 14/27 = 9x2/-7x7 x 2x7/9x3 = 4/-21

c) 45/28 x 7/-15 = 5x-3x-3/ 7x4 x 7/-3x5 = -3/4

d) 21/32 x 108x49= 7x3/4x8 x 4x27/7x7 = 81/56

e) -26x -5/39 = 13x-2 x -5/13x3 = 10/3

f) 8/2 x -5/21 (-9/16)= 8/5 x 5x-1/3x7 x 3x-3/8 = -3/7