Question

How many terms of the A.P. 9,17,25... must be taken to give a sum of 636?

Answer 1

AP=9,17,25,....... Let no. of terms be n a=9 d=17-9=8 S=sum of n terms=636 We know; S=n/2[2a+(n-1)d] 636=n/2[2×9+(n-1)8] 636=n/2[18+8n-8] 636×2=n(10+

Answer 2

answer..............