If a−b=6, then find the value of a3−b3−18ab
108
216
36
54
Given: a−b=6
Taking cube of the given equation, we get
(a−b)3=63=216
⇒a3−b3−3ab(a−b)=216
⇒a3−b3−3ab×6=216
⇒a3−b3−18ab=216
If a - b = 6 and ab = 20, find the value of a3−b3.