1. express 21 as the sum of two prime numbers
Solution:
We can write `21` as
`2+19=21`
2. express 44 as the sum of two prime numbers
Solution:
We can write `44` as
`3+41=44`
3. express 24 as the sum of two prime numbers
Solution:
We can write `24` as
`5+19=24`
4. express 21 as the sum of three prime numbers
Solution:
We can write `21` as
`2+2+17=21`
`3+5+13=21`
`3+7+11=21`
`5+5+11=21`
`7+7+7=21`
5. express 21 as the sum of three odd prime numbers
Solution:
We can write `21` as
`3+5+13=21`
`3+7+11=21`
`5+5+11=21`
`7+7+7=21`
6. express 49 as the sum of three odd prime numbers
Solution:
We can write `49` as
`3+3+43=49`
`3+5+41=49`
`3+17+29=49`
`3+23+23=49`
`5+7+37=49`
`5+13+31=49`
`7+11+31=49`
`7+13+29=49`
`7+19+23=49`
`11+19+19=49`
`13+13+23=49`
`13+17+19=49`
7. express 31 as the sum of three odd prime numbers
Solution:
We can write `31` as
`3+5+23=31`
`3+11+17=31`
`5+7+19=31`
`5+13+13=31`
`7+7+17=31`
`7+11+13=31`
This material is intended as a summary. Use your textbook for detail explanation.
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