Binomial Theorem need help

Just doing some extra works to check my knowledge, found these questions from the HKDSE (which is equivalent to A level), but it's really hard, anyone gives a thought?


https://www.flickr.com/photos/124072059@N08/13944461528/

Why do you think they are really hard?

They do not use any more additional knowledge than an A Level question

The one with the ratio is badly worded - is this a translation?

I don't know if it is translation or not, but I agree with you it's badly worded, maybe the English of Maths teachers in Hong Kong is not very good.

Back to the maths, I have never come across with a question like this, how would you solve it

The ratio question or generally?

I would say Q2 and Q3 are hardest. If you have time please show all question. Huge appreciation