Compare the following two decimal fractions by replacing the with the correct relationship sign <, > or =.

4,501 is greater than 4,500.

b) Compare 3,101 and 3,011.

The whole number part is 3 for both.

1 in 3,101 and 0 in 3,011.
Since $1 > 0$, 3,101 is greater than 3,011.

c) Compare 4,12 and 4,1201.

4,1200 is less than 4,1201.

2. Arrange the following decimal fractions in ascending order:
$7,01; 0,701; 0,71; 7,34; 7,0101; 71,01; 7,034$

7,0100
0,7010
0,7100
7,3400
7,0101
71,0100
7,0340

The smallest numbers are those with 0 as the whole number part: 0,7010 and 0,7100.
Comparing 0,7010 and 0,7100: $0,7010 < 0,7100$.

Next are numbers with 7 as the whole number part: $7,0100; 7,3400; 7,0101; 7,0340$.
Comparing these:
7,0100
7,0101
7,0340
7,3400

Finally, the largest number is 71,0100.

3. Complete the following sequences:

a) $4,5; 5; 5,5; 6; 6,5 ...$ up to 8

Each term increases by 0,5.

4,5
5 ($4,5 + 0,5$)
5,5 ($5 + 0,5$)
6 ($5,5 + 0,5$)
6,5 ($6 + 0,5$)
7 ($6,5 + 0,5$)
7,5 ($7 + 0,5$)
8 ($7,5 + 0,5$)
The completed sequence is: $\boxed{4,5; 5; 5,5; 6; 6,5; 7; 7,5; 8}$

b) $3,8; 3,6; 3,4; 3,2 ...$

Each term decreases by 0,2.

3,8
3,6 ($3,8 - 0,2$)
3,4 ($3,6 - 0,2$)
3,2 ($3,4 - 0,2$)
3,0 ($3,2 - 0,2$)
2,8 ($3,0 - 0,2$)
2,6 ($2,8 - 0,2$)
The next few terms in the sequence are: $\boxed{3,0; 2,8; 2,6}$