the 2nd and 45th term of an ap are 10 and 96 respectively.Find the first term and the common differenceand hence find the sum of first 15 terms
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Heya Frnd........☺
✴ Note :- a = 1st term
d = difference
2 nd term = a + d = 10
45 th term = a + 44 d = 96
Now,
( a + 44d) - ( a + d) = 96 - 10
43 d = 86
Therefore ,
d = 86/43 = 2......... (1)
Now ,
a + d = 10
=> a = 10 - d
=> a = 10 - 2 = 8 ................ ( 2 )
Now,
Sₙ = n/2 (2a + (n-1)d)
=> 15/2 ( 2*8 + (15 - 1)2)
=> 15/2 ( 16 + 28)
=> 15/2 * 44
=> 15 * 22
=> 330 ........................( 3 )
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✴ Note :- a = 1st term
d = difference
2 nd term = a + d = 10
45 th term = a + 44 d = 96
Now,
( a + 44d) - ( a + d) = 96 - 10
43 d = 86
Therefore ,
d = 86/43 = 2......... (1)
Now ,
a + d = 10
=> a = 10 - d
=> a = 10 - 2 = 8 ................ ( 2 )
Now,
Sₙ = n/2 (2a + (n-1)d)
=> 15/2 ( 2*8 + (15 - 1)2)
=> 15/2 ( 16 + 28)
=> 15/2 * 44
=> 15 * 22
=> 330 ........................( 3 )
________________________
________________________
HOPE IT WILL HELP YOU. . . . . . . . . ☺
PLZ MARK MY ANSWER AS BRAINLIEST IF U LIKE IT. . . . . . . . . . . . . . ✴
⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐⭐
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