The sum of first n terms of arithmetic sequence is 2n square + 3n? sum of first ten terms? first term and common difference? arithmetic expression of sequence? 20th term of sequence?
Answers
Answer:
Sum of first n terms of an arithmetic sequence is 3n
2
+n.
Let a
1
denotes first term of the sequence,
a
2
denotes second term of the sequence,
d denotes common difference of the sequence,
S
n
denotes sum of first n terms of the sequence.
S
n
=3n
2
+n
S
1
=a
1
=3(1)
2
+1=4
S
2
=a
1
+a
2
=3(2)
2
+2=14
∴a
1
+a
2
=14
∴a
1
+a
1
+d=14
∴2a
1
+d=14
∴2(4)+d=14
∴d=6
First term of the sequence is 4 and common difference is 6.
Step-by-step explanation:
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Step-by-step explanation:
Answer
Sum of first n terms of an arithmetic sequence is 3n
2
+n.
Let a
1
denotes first term of the sequence,
a
2
denotes second term of the sequence,
d denotes common difference of the sequence,
S
n
denotes sum of first n terms of the sequence.
S
n
=3n
2
+n
S
1
=a
1
=3(1)
2
+1=4
S
2
=a
1
+a
2
=3(2)
2
+2=14
∴a
1
+a
2
=14
∴a
1
+a
1
+d=14
∴2a
1
+d=14
∴2(4)+d=14
∴d=6
First term of the sequence is 4 and common difference is 6.