The nth term of a sequence is given by 20-n^2 a) find the third term of the sequence b) which term in the sequence is the first to have a negative value

The third term is 11.

The first negative term is the fifth term.

Step-by-step explanation:

If the nth term of the sequence is given by the expression 20-n^2, to find the third term, we just need to use the value of n = 3 in the expression:

20 - (3) ^2 = 20 - 9 = 11.

To find which term is the first to have a negative value, we can solve the inequation 20 - n^2 < 0:

20 - n^2 < 0

n^2 > 20

n > 4.47

The first term to have a negative value is the fifth term:

20 - 5^2 = 20 - 25 = - 5