bonjour pouvez vous m aider svp et merci :)​

Bonjour,

ab +bc

( 2/3 ) (1/4) + (1/4)( 2/5)

= 2/12 + 2/20

= 1/6 + 1/5

= 5/30 + 6/30

= 11/30

(a+d) / (b+c)

= (2/3 -1/2) /  ( 1/4 + 2/5)

= ( 4/6 - 3/6) / ( 5/20 + 8/20)

= 1/6 / 13/20

= 1/6 * 20/13

= 20/ 78 = 10/ 39

a-b

= 2/3 - 1/4

= 8/12 - 3/12

= 5/12

bonjour

a = 2/3  ;  b = 1/4  ;  c = 2/5  ; d = -1/2

A = (2/3)(1/4) + (2/5)(-1/2)

  = (2 x 1)/(3 x 4) - (2 x 1)/(5 x 2)

 = (1 x 1)/ (3 x 2) - (1 x 1) / (5 x 1)

 = 1/6 - 1/5

 = 5/30 - 6/30 = -1/30

B

a + d = 2/3 - 1/2 = 4/6 - 3/6 = 1/6

b + c  = 1/4 + 2/5 = 5/20 + 8/20 = 13/20

B = (1/6) / (13/20) = (1/6) x (20/13) = 20 / (6 x 13) = 10/(3 x 13) = 10/39

C = a - b = 2/3 - 1/4 = 8/12 - 3/12 = 5/12