Question

if the pth term of an ap is Q and its qth term is P then what is n th term

Answer 1

Tp=q
a+(p-1)d=q..(1)

Tq=p
a+(q-1)d=p..(2)
subtract (1) and (2)
we get
(p-q) d=q-p
therefore d=-1
putting value of d in (1)

a+(p-1)(-1)=q
therefore a=q+p-1

now for n th term
Tn=a+(n-1)d
q+p-1+(n-1)(-1)
q+p-n...(your answer).