Which term of the AP 24, 21, 18, 15... is the first negative term

Explanation

`T_n = a+(n-1)d`

`a = 24`

`d= 21-24 = -3`

`T_n = 24 + (n-1)(-3)`

`T_n = 24 - 3n + 3 = 27 - 3n`

`T_n < 0`

`27-3n < 0`

`27 < 3n`

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