Question

how many term are there in A.P. 18,31/2,13-------,47?
PLZ ANSWER IT QUICKLY
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Answer 1

First term, a = 18

Second term, a2 = 31 / 2

Common difference, d = 31/2 - 18 = - 5 / 2


An = a+ ( n - 1 ) d

47 = 18 + ( n - 1 ) ( - 5 / 2 )

47 - 18 = ( n - 1 ) ( - 5/ 2 )

29 * 2 / 5 = ( n - 1 )

58/5 = n - 1

n = 11. 6 + 1 = 12. 6 or 13 terms.

Answer 2

HERE IS YOUR ANSWER

THE 47 SHOULD BE -47

the first number in the A.P is 18 = A1 = A

the common difference = 31/2 - 18 = -5/2 = d

An = -47 = A + ( n - 1 ) × d

-47 = 18 + ( n - 1 ) × -5/2

( -47 - 18 ) × -2 /5 = n - 1

(-65 × -2 / 5 ) + 1 = n

26 + 1 = n

n = 27

THEREFORE THERE ARE 27 TERMS IN THE A.P

HOPE MY ANSWER IS CORRECT