Sagot :
Exercice 1
A= 3/7 +4/21-5/2
= 12/21 - 5/2
= -79/42
Exercice 2
B= 3/5 - 1/5 X (5/2+2)
= 3/5 - 1/5 X (9/2)
= 3/5 - 9/10
= - 3/10
Exercice 3
b = 2/3-4/3x5/2
= 2/3 -20/6
= 2x2/3x2 - 20/6
= 4/6 - 20/6
= 16/6
= 8/3
C = 5 + ( 1+1/8 ) : 3/4
= 5 + ( 1/8 ) : 3/4
= 5 +3/2
= 5/1 + 3/2
= 5x2/1x2 + 3/2
= 10/2 + 3/2
= 13/2
Voila :)
exercice1 : = 3*3/7*3+4/21-5/2
=9/21+4/21-5/2
=13/21-5/2
=13*2/21*2-5*21/2*21
=26/42-105/42
=-79/42
exercice2 : =3/5-1/5*(5/2+4/2)
=3/5-1/5*9/2
=3/5-2/10*45/10
=3/5-9/10
=6/10-9/10
=-3/10
exercice3 je c pas ;)