Answer:
Tn = 34+3n
Step-by-step explanation:
The formula for finding the nth term of an arithmetic sequence is expressed as shown;
[tex]Tn = a+(n-1)d[/tex]
a is the first term of the sequence
n is the number of terms
d is the common difference
If T₁₂ = 70 and T₃₀ = 124
T₁₂ = a+(12-1)d = 70
T₁₂ = a+11d = 70... (1)
Similarly;
T₃₀ = a + (30-1)d = 124
T₃₀ = a +29d = 124...(2)
Solving equation 1 and 2 simultaneously to get a and d.
Subtracting 2 from 1 we have;
29d - 11d = 124-70
18d = 54
d = 54/18
d = 3
Substituting d = 3 into equation 1 to get a we have;
a + 11(3) = 70
a + 33 = 70
a = 70-33
a = 37
The explicit rule for the nth term of the sequence can be gotten by substituting the value of a and d into the formula Tn = a+(n-1)d
Tn = 37+(n-1)*3
Tn = 37+3n-3
Tn = 34+3n
