A quick trip through a nice lecture on the Binomial Theorem should get you started.
PHYS208 Binomial Theorem
Expand (1-8x)^1/2 as far as the term in x^2
Put x= -1 to obtain an approximation to (square root of) 5
Find the next term in the expansion and hence find two values between which (square route) 5
im clueless, dont even understand the question
no mate, everyone in the class has just handed in the assignment without doing the question but i dont like doing that
Is ther not just a simple tutorial, or a worked example of a the same kind of question you (or anybody) could show me, it would be a great help