All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.

(i)

(ii)

Since r is an integer,

### KS Comments:

(ii) is honestly not easy. Some students didn’t know the formula which is puzzling as the formal is given in MF15. I think it is important that students knows what formulas they are given in exams so they can utilise they properly.

[…] Question 11 (Note Worthy) […]