To find the nth term and the three terms of the arithmetic sequence, we first need to determine the common difference (d) and the first term (a1).
Given:
a4=93
a8=65
Step 1: Find the common difference (d).
In an arithmetic sequence, the nth term can be expressed as an=ak+(n−k)d.
Using a8 and a4:
a8=a4+(8−4)d
a8=a4+4d
Substitute the given values:
65=93+4d
Subtract 93 from both sides:
65−93=4d
−28=4d
Divide by 4:
d=4−28
d=−7
Step 2: Find the first term (a1).
The general formula for the nth term of an arithmetic sequence is an=a1+(n−1)d.
Using a4=93 and d=−7:
a4=a1+(4−1)d
93=a1+3(−7)
93=a1−21
Add 21 to both sides:
a1=93+21
a1=114
Step 3: Find the nth term (an).
Using the general formula an=a1+(n−1)d with a1=114 and d=−7:
an=114+(n−1)(−7)
an=114−7n+7
an=121−7n
Step 4: Find the first three terms of the sequence.
The first term is a1=114.
The second term is a2=a1+d=114+(−7)=107.
The third term is a3=a2+d=107+(−7)=100.
The nth term of the arithmetic sequence is ∗121−7n∗.
The first three terms of the sequence are ∗114,107,100∗.