2. Observe Arithmetic sequence 3n+1.
(a)Find the first term and common difference of the sequence.
(b)Find the 20" term of the Sequence.
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Answer:
Given,
a1+a20=88
a.
a2+a19
=(a1+d)+(a20−d)
=a1+a20
=88
b.
a10+a11=a1+9d+a20−9d
42+a11=a1+a20
∴a11=88−42=46
c.
d=a11−a10
=46−42=4
d.
a10=a+9d
a=42−9(4)
∴a=6
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