Factorise the following expressions. 1) x3 + 8y3
2) 8x3-27y3
3) a3-8b3
4) 8a3+27b3
5) a3-64

Explanation:

Both are cubes so

1.(x + 2y)

2.(2x - 3y)

3. (a - 2b)

4. (2a + 3b)

5. (a - 4)

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

the temperature of the gas, in k, not celsius.