Question icon
Grade 11Algebra

If (1+x)(1+x2)(1+x4).......(1+x128)=∑xr where r=0 and limit is n. So find the value of n.

Profile image of Sarvesh Chavhan
7 Years agoGrade 11
Answers icon

1 Answer

Profile image of Aditya Gupta
ApprovedApproved Tutor Answer7 Years ago
since (1+x)(1+x2)(1+x4).......(1+x128)=∑xwhere r=0 and limit is n, all we gotta do is to find the degree of the polynomial on LHS, which is equal to 1+2+4+....128
this is a GP with common ratio 2, so sum is:
S=1*(2^8 – 1)/(2 – 1)
so n=S=2^8 – 1
n= 255