A(1)=20
a(n)=a(n−1)−17
find the 3rd term in the sequence

The third term is -14



Explanation:

First term = A(1) = 20, which is given

Second term
A(n) = A(n-1) - 17
A(2) = A(2-1) - 17
A(2) = A(1) - 17 note: second term = (first term) - 17
A(2) = 20 - 17
A(2) = 3

Third term
A(n) = A(n-1) - 17
A(3) = A(3-1) - 17
A(3) = A(2) - 17 ... note: third term = (second term) - 17
A(3) = 3 - 17
A(3) = -14