Rationalise the following: 1/root -7 - root-3

If value of cos330° is √3/2 then find tan165°.

Factor the polynomial expression x6 – x3 – 20

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)