MCQ
The first term of an $A.P.$ if its $S_n=n^2+2 n$ is :
- ✓$3$
- B$0$
- C$1$
- D$2$
✓
Answer
Correct option: A.
$3$
Given : $S_n=n^2+2 n$
Putting $n=1,$ we get
$S=a=(1)^2+2 \times 1$
$=1+2=3$
Putting $n=1,$ we get
$S=a=(1)^2+2 \times 1$
$=1+2=3$
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