MCQ
Which term of the $AP 72, 63 54, ....$ is $0?$
- A$8^{th}$
- ✓$9^{th}$
- C$10^{th}$
- D$11^{th}$
✓
Answer
Correct option: B.
$9^{th}$
The given $AP$ is $72, 63, 54, .....$
$a = 72$ and $d = 63 - 72 = -9$
$a_n = a + (n - 1)d$
$\Rightarrow 0 = 72 + (n -1)(-9)$
$\Rightarrow -72 = (n - 1)(-9)$
$\Rightarrow 8 = n - 1$
$\Rightarrow n = 9$
So, the $9^{th}$ term is $0.$
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