A- a sous forme de fraction
a=6/7 -4/7*5/2 = 6/7 - 20/14 = 6/7 - 10/7 = (6-10)/7 = -3/7
- b sous forme entier
b = (3/4-4)/(3/4+1/3) = ( 3/4-16/4 )/( 9/12+4/12) = (-13/4)/(13/12)
b= (-13/4)*12/13 = -13/4*12/13 = -12/4 = 3
b - c sous forme decimal
c= 3²*2-125*10-1 = 9*2-125*10-1 = 18-12.5 = 5.5
- d ecriture scientifique
d=3.2*10-5*5*10ex5 /4*10-2 = 3.2*5*10-5*10ex5/4*10-2
d= 16/4*10-2 = 4*10²