kalakadu.com: Find the indicated terms of the sequences whose nth terms are given by (ii) an = -(n2

Find the indicated terms of the sequences whose nth terms are given by

(ii) an = -(n2 - 4); a4 and a11

Solution :

To find a4, we have to apply 4 instead of n.

To find a11, we have to apply 11 instead of n.

an = -(n2 - 4)

n = 4

a4 = -(42 - 4)

a4 = -(16 - 4)

= -12

an = -(n2 - 4)

n = 11

a11 = -(112 - 4)

a11 = -(121 - 4)

= -117