Question

It addedb to the sum of the first few terms of the algebraic sequence 9,11,13,... gives 256.how many terms are added?

Answer 1

Answer:

Sum = 256

a = 9

d = 2

Sum = (n/2) *(2a+(n-1)d)

256 = (n/2)*(2*9+(n-1)*2)

512= n*(18+2n-2)

512= n*(2n-16)

216= n*(n-8)

n^2 - 8n - 216 = 0

n = 19.231546211727817

Or

Near to

n = 20