Saved Bookmarks
| 1. |
The sum of first n of an ap is given by SN is equal to 2nsquare + 3 and find the 16 term of AP |
|
Answer» There is a mistake in a question.I think question is like thisQuestion:The sum of first n terms of an AP is given by Sn = 2n² + 3n . Find the sixteenth term ofthe AP.Solution:Let an be the nth term & Sn be the sum of first n terms.Given:Sn = 2n²+3nan = S(n) - S(n-1)=2n²+3n -[ 2(n-1)²+3(n-1)]= 2n²+3n -[2(n²+1-2n)+3n -3]= 2n²+3n -[2n²+2-4n + 3n -3]= 2n²+3n -2n²+4n-3n -2+3= 2n²+2n²+3n -3n +4n -2+3= 4n +1an = 4n+1a16= 4×16 +1= 64+1= 65Hence, the 16th term of an AP is 65 -----> a16 = 20........ |
|