write down and simplify the expression of (1-p)^5 .Use this result to find the expansion of (1-x-x^2)^5 in ascending powers of x as far as the terms in x^3 . Find the value of x which would enable you to estimate (0.9899)^5 from this expansion
Any further terms will have multiplication by 0 so there are no more terms. I'll leave simplifying that to you.
What the next question is asking is to substitute for p in the above expansion. You can either do this as above or substitute , if you use the latter remember that the whole expression is squared.
For the third part it is asking you to solve and where q is a constant.