Answer:
77.
Step-by-step explanation:
an = a1 + (n-1)d where d is the common difference.
a12 = a1 + 11d
22 = a1 +11(-5)
22 = a1 - 55
a1 = 22 + 55
a1 = 77.
The first term of the arithmetic series can be obtained using the relation, A12 = a1 + 11d ; Hence, the first term is 77
To obtain the nth term of an arithmetic series ; use the relation :
The 12th term can be defined as :
22 = a1 + 11(-5)
22 = a1 - 55
22 + 55 = a1
a1 = 77
Therefore, the first term of the arithmetic series is 77
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