répondez svp !!!!!!!!!!!!!

# M = - 1/2 + 7/4 * 5/9

Préliminaires :

-1/2 = - 2/4

1= 9/9

Donc :
M =-1/2 + 7/4 * 5/9
M= - 2/4 + 7/4 * 5/9
M= - 2/4 * 9/9 + 7/4 * 5/9
M= (-2*9+7*5 )/ (4*9)
M = (-18 +35) / (36)
M = 17/36

#. N = - 5/3 *(-4/7 - -9/28)

Préliminaires :
-4/7 = (-4*4)/(7*4) =-16/28
7/28 =1/4

N = - 5/3 * ( - 16/28 - -9/28)
N = - 5/3 * (-16/28 +9/28)
N = - 5/3 * (-16+9)/28
N = - 5/3 * 7/28

N = -5/3 * 1/4
N = (-5 *1) / (3 * 4)
N = - 5/ 12


#. P= (2/7 - 3/14) * (-5/6 - 2/9)

Préliminaires:
2/7 = (2*2)/(7*2) = 4/14
-5/6 = (-5*3)/ (6*3) = - 15/18
2/9 = (2*2)/(9*2) = 4/18

Donc
P = (4/14 - 3/14) * (-15/18 - 4/18)
P = (4-3)/14 *(-15-4)/18
P = 1/14 * (-19) /18

P = (1 * - 19)/ (14*18)
P = - 19 / 252