Question

Consider a sequence that follows a minus 5 pattern: 30, 25, 20, 15, ….

b. Using the formula, find the 20th term of the sequence.

Answer 1

`a_2_0=-65`

Explanation:

As we can see, the sequence starts from 30 and decreases by 5 each time. So, one possible formula for that sequence could be:

`a_n=35-5n\hspace{10}n\in N`

Let's confirm the formula by evaluating the first 4 terms:

`a_1=35-5(1)=35-5=35\\a_2=35-5(2)=35-10=25\\a_3=35-5(3)=35-15=20\\a_4=35-5(4)=35-20=15`

Finally evaluating n=20:

`a_2_0=35-5(20)=35-100=-65`