Question
Which term of the $AP\ 72, 68, 64, 60, .....$ is $0?$
✓
Answer
In the given $AP,$ we have $a =72$ and $d = 68 - 72 = -4$
Suppose there are $n$ terms in given $AP,$ we have
$T_n= 0 ⇒ a + (n - 1)d = 0 $
$⇒ 72 + (n - 1)(-4) = 0$
$⇒ 72 - 4n + 4 = 0$
$⇒ 4n = 76 ⇒ n = 19$
Hence, the $19^{th}$ term in the given $AP$ is $0.$
Suppose there are $n$ terms in given $AP,$ we have
$T_n= 0 ⇒ a + (n - 1)d = 0 $
$⇒ 72 + (n - 1)(-4) = 0$
$⇒ 72 - 4n + 4 = 0$
$⇒ 4n = 76 ⇒ n = 19$
Hence, the $19^{th}$ term in the given $AP$ is $0.$
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