Let the roots of equation x2−6x+a=0 be α and 4β and that of the equation x2−cx+6=0 be α and 3β. Then α+4β=6;‌‌4αβ=a and ‌‌α+3β=c;‌‌3αβ=6 ⇒‌‌a=8 ∴ The equation becomes ‌x2−6x+8=0 ‌⇒(x−2)(x−4)=0 ⇒ roots are 2 and 4 ⇒α=2,β=1 ∴ Common root is 2 .