Answers

2015-11-21T21:11:34+05:30
S3 = 36
S3 =n/2[2a+(n-1)d]=36
        3/2[2a+(3-1)d] =36
        2a+2d =36 x 2/3
        2a +2d =24.......let the equation be 1
a5 =15
 (a +4d =15) x 2
2a + 8d = 30.....let the equation be 2
 
    equation 2-1, gives
  2a +8d =30
 2a + 2d =24

⇒6d = 6
  ⇒d =1 
 substitute in any equation
   2a + 2d =24
  2a +2x1 =24    (d=1)
 2a +2 =24 
2a =24-2
2a=22
a=22/2
⇒a=11 
  
⇒a1 = a =11
a2 =a+d =11+1 =12
a3 = a=2d = 11+2x1 =11+2 =13
a4 =a+3d = 11+3x1 =11+3  =14

∴The series is 11,12,13,14,15............



       
0