Find the indicated terms of the sequences whose nth terms are given by (ii) an = -(n2 - 4); a4 and a11

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