x2–16x+39=0 ⇒x–3x–13x+39=0 ⇒x(x–3)–13(x–3)=0 ⇒(x–3)(x–13)=0 either, x–3=0 or,x–13=0 ∴ x=3 or x=3 or x=13 Here, m = 3 and n = 13, (m < n) Given, four terms p, q, r and s are inserted between m and n to form in A.P. ∴ 3, 5, 7, 9, 11, 13 are in A.P. ∴p=5,q=7,r=9,s=11