What is the 12th term of the sequence 5, 12, 19....?

2 Answers
Mar 6, 2016

82

Explanation:

The Sequence equation is: Tn=7n-2
T12th=7x12-2

T=TERM
N=Which term( 1st,2nd,3rd)
the sequence is going up in seven's and you wouldn't want to start with 7 for the equation so how do you get from 7 to 5? Subtract 2.
Then for a term you're trying to find just add it into the sequence equation. Practice this!

Mar 23, 2016

82

Explanation:

We observe that difference between first and second terms =12-5=7
Similarly difference between second and third terms =19-12=7

It shows that the given sequence of numbers is an arithmetic progression with common difference equal to 7.

We know that nth term of an AP whose first term is a_1 and whose common difference is d is given by
a_n = a_1 + (n – 1) d

To find the 12th term, insert given values in the general expression
a_12 = 5 + (12 – 1) 7
a_12 = 5 + (11) 7=5+77=82