Let f(x) is continuous at x=1, then f(1−)=f(1)=f(1+) ⇒5=a+b ....(1) Let f(x) is continuous at x=3, then f(3−)=f(3)=f(3+) ⇒a+3b=b+15 ......(2) Let f(x) is continuous at x=5, then f(5−)=f(5)=f(5+) ⇒b+25=30 ⇒b=30−25=5 From (1),a=0 But a=0,b=5 do not satisfy equation (2) Hence, f(x) is not continuous for any values of a and b