1.

Which term of the AP -3,3,9….. is 117

Answer»

GIVEN:-

⠀⠀⠀◍ AP = -3 , 3 , 9 ......

⠀⠀⠀◍ an = 117

⠀⠀

To find:-

⠀⠀⠀◍ The value of n.

⠀⠀

Identity USED:-

⠀⠀⠀◍ an = a+ (n -1) d.

⠀⠀

Solution:-

⠀⠀⠀◍ Value of d = a2 - a1

⠀⠀⠀◍ d = 3 - (-3)

⠀⠀⠀◍ d = 6

⠀

⠀⠀⠀✯ an = a + (n - 1)d

⠀⠀⠀✯ 117 = -3 + (n - 1)6

⠀⠀⠀✯ 117 + 3 = 6N - 6

⠀⠀⠀✯ 120 + 6 = 6n

⠀⠀⠀✯ \sf\dfrac{\cancel{126}}{\cancel{6}}

⠀⠀⠀✯ n = 21

⠀⠀

Answer:-

⠀⠀⠀★ 21st TERM of an AP -3 , 3 , 9 , ..... is

⠀⠀⠀⠀ 117.


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