Question

find the sum upto n terms;

1/2X5+1/5X8+1/8X11+..........

Answer 1

Answer is nChange every term in difference of 2 terms by multiplying and dividing by 2After this- 2 in numeratorcan be written as=3-1=5-3=7-5....=2n+1-2n-1 then rationalise every term . You will fond that starting term get cancelled by ending term of succedding groupof term=1/2(2n+1-1)=n Here i cannot write the answer as i do not know how to write squre root