A = √21 + √42 + √63 và B = √1 + √2 + √3 + √20 + √40 + √60

To simplify the expressions for \( A \) and \( B \), let's evaluate each square root term.

### Calculation of \( A \):
1. \( \sqrt{21} \) remains as is.
2. \( \sqrt{42} = \sqrt{6 \cdot 7} = \sqrt{6} \sqrt{7} \) remains as is.
3. \( \sqrt{63} = \sqrt{9 \cdot 7} = 3\sqrt{7} \).

So,
\[
A = \sqrt{21} + \sqrt{42} + 3\sqrt{7}.
\]

### Calculation of \( B \):
1. \( \sqrt{1} = 1 \).
2. \( \sqrt{2} \) remains as is.
3. \( \sqrt{3} \) remains as is.
4. \( \sqrt{20} = \sqrt{4 \cdot 5} = 2\sqrt{5} \).
5. \( \sqrt{40} = \sqrt{4 \cdot 10} = 2\sqrt{10} \).
6. \( \sqrt{60} = \sqrt{4 \cdot 15} = 2\sqrt{15} \).

So,
\[
B = 1 + \sqrt{2} + \sqrt{3} + 2\sqrt{5} + 2\sqrt{10} + 2\sqrt{15}.
\]

### Final Expressions:
Thus, the simplified forms are:
\[
A = \sqrt{21} + \sqrt{42} + 3\sqrt{7}
\]
\[
B = 1 + \sqrt{2} + \sqrt{3} + 2\sqrt{5} + 2\sqrt{10} + 2\sqrt{15}
\]

Further calculation can be done based on the specific needs, but these are the simplified forms for \( A \) and \( B \).