The the numbers - 15 - 11 - 7 - 3 are in the arithmetic
what is the term say answer please give me your
Answers
Answered by
1
Answer:
ANSWER : n = 14
Sn = 406
a = 3
d = 7 - 3 = 4
n = ?
Sn = n/2 ( 2a + (n-1) d)
406 = n/2 ( 2 x 3 + (n-1) 4)
406 x 2 = n ( 6 + 4n -4)
812 = n ( 2 + 4n)
812 = 2n + 4n sq.
4n sq. + 2n - 812 = 0
2n sq. + n - 406 = 0. .....[ taking 2 common ]
2n sq. - 28n + 29n - 406 = 0
2n ( n - 14) + 29 ( n - 14) = 0
(2n + 29) (n-14) = 0
2n + 29 = 0
n = -29/2
n - 14 = 0
n = 14
SINCE VALUE OF n CANNOT BE IN FRACTION, THEREFORE n = 14
Step-by-step explanation:
Similar questions