Answer:
18 terms
Step-by-step explanation:
The first given sequence has first term a1=2 and common difference d=5. Its explicit formula is ...
an = 2 +5(n -1) = 5n -3
We want the n-th term of this sequence to be the same as the n-th term of the sequence defined by ...
an = 4n +15
We can find n that makes this true by setting the 'an' values equal:
an = an
5n -3 = 4n +15
n = 18 . . . . . . . . . . add 3-4n
The number of terms in each sequence is 18.
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Additional comment
The last term in each sequence is 87.
