Question

Ex 9 . Va dau 15 puncte pentru raspuns

Answer 1

a)
3,8(3)=(383-38)/90=345/90=23/6
2,(54)=(254-2)/99=252/99=28/11
2,(3)=(23-2)/9=21/9=7/3
(23/6-28/11×11/28):7/3=(23/6-1):7/3=(23-6)/6 ×3/7=17/6×3/7=17/14

b)0,(5)=5/9
1,(75)=(175-1)/99=174/99=58/33
0,3(6)=(36-3)/90=33/90=11/30
0,19(60)=(1960-19)/9900=1941/9900=647/3300
2 5/13=31/13
[5/9+58/33+11/30]:(1/4+31/13+109/156)+647/3300=
=(550+1740+363)/990 :(1/4+31/13+109/156)+647/3300=
=2653/990 :(39+372+109)/156)+647/3300=
=2653/990 ×156/520+647/3300=
=2653/990 ×3/10+647/3300=
=2653/3300+647/3300=
=3300/3300=1

c) 123456,789×8+0,009-(12345,678×80+0,09)=
= 123456,789×8+0,009-123456,78×8-0,09=
=8(123456,789-123456,78)+0,099=
=8×0,009+0,081=0,072-0,081=-0,009

d) [0,278:13,9+(2-0,47):3/20]:102,2+3,4×1 4/17=
= [0,02+1,53×20/3]:102,2+3,4×21/17=
= (0,02+10,2):102,2+0,2×21=
= 10,22:102,2+4,2=
=0,1+4,2=4,3