MCQ
Which term of the $AP\ \ \{ 72, 63 54, ....\}$ is $0$ ?
- A$8^{\text {th }}$
- ✓$9^{\text {th }}$
- C$10^{\text {th }}$
- D$11^{\text {th }}$
✓
Answer
Correct option: B.
$9^{\text {th }}$
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 $0$.
$a = 72$ 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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