Question

Find the 50th term of the sequence 5, –2, –9, –16, ...

–352
–343
–338
–331

Answer 1

The correct answer: -338

Answer 2

The sequence 5, -2, -9, -16... is a arithmetric sequence with the difference between a number and its succeding term is -7. The formua for getting the nth term of an arithmetric sequence is

`a_n = a_1 + (n-1)d`
where
`a_n` is the nth term

`a_1` is the first term
n is the number of terms
d is the difference

The first term in the sequence is 5. You need to find the 50th term so n is 50. The difference (d) is -7. Substituting these values in the equation, we get the final answer

`a_(50) = 5 + (50-1)(-7) \\ a_(50) = -338`

The 50th term is -338.