Question

The sum of first n terms of an ap is given by sn=3n2-4n determine the ap of its 12th term

Answer 1

S1=3(2-4)= -6
S2=6(2-8)= -36
S1 =a1= -6
S2-S1= a2= -36+6= -30
d= a2-a1 -30+6= -24
a12= 6+11(-24)= 6-264=-258