Question

How many terms of tha series 5+7+9... must be taken in order that tha sum me be 480?

Answer 1

A =5

d=2

sn=n/2(2a+(n-1)d)

480=n/2(10+2n-2)

480=n/2(2(4+n)

n^2+4n-480=0 solve it

Answer 2

Here's your answer. :)