the sum of the first n term of an ap is 3n-n^2. what is the first term. what is the sum of first term. what is the second term. similarly find the 3rd, the 10th term and nth terms.
Answers
Answered by
1
Answer:
Here S
n
=3n+n
2
Now, first term a=S
1
⇒a=3×1+1
2
=4 and
Sum of first two terms=a
1
+a
2
=a+(a+d)=S
2
=3×2+2
2
=10
⇒2a+d=10⇒8+d=10⇒d=2
Now, a
2
=a+d⇒a
2
=4+2=6
a
3
=a+2d⇒a
3
=4+2×2=8
a
15
=a+14d⇒a
15
=4+14×2=32
Step-by-step explanation:
hope it helps you
mark me brainliest
Similar questions