MCQ
The $n^{th}$ term of the $A.P. a, 3a, 5a, .........$ is.
- A$na$
- B$(2n – 1) a$
- ✓$(2n + 1) a$
- D$2na$
✓
Answer
Correct option: C.
$(2n + 1) a$
$a = a, d = 3a - a = 2a$
$A_n= a + (n - 1)d$
$= a + (n - 1)2a$
$= a{1 + 2(n - 1)}$
$= a{1 + 2n - 2}$
$= a(2n - 1) = (2n - 1)a$
$A_n= a + (n - 1)d$
$= a + (n - 1)2a$
$= a{1 + 2(n - 1)}$
$= a{1 + 2n - 2}$
$= a(2n - 1) = (2n - 1)a$
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