write down the binomia expansion of (1+y)^8 where y=x+x² as far as the term x^6

Answer 1

(1+y)^8 , for y = x+x^2
= 1 + 8y + 28y^2 + 56y^3 + 70y^4 + 56y^5 + 70y^6 + ..
= 1 + 8(x+x^2) + 28(x+x^2)^2 + 56(x+x^2)^3 + 70(x+x^2)^6 + ...
( the remaining terms will contain x^7 and higher )
= take over, take care in the expansions

or

look up trinomial expansion here:
https://www.qc.edu.hk/math/Advanced%20Level/Trinomials.htm

Answer 2

great! i am very happy with this.... i will make sure i study it well