Q. 85.0( 2 Votes )

If x – y = – 6 and xy = 4, find the value of x3 – y3

Answer :

The identity used here is


(a + b)3 = a3 + 3a2b + 3ab2 + b3


(x – y)3 = x3 + 3x2(– y) + 3x(– y)2 + (– y)3


x3 – 3x2y + 3xy2 – y3


(x – y)3 = x3 – 3x2y + 3xy2 – y3


(– 6)3 = x3 – y3 + 3xy(– x + y)


– 216 + 3 × 4 (– 6) = x3 – y3


– 216 – 72 = x3 – y3


– 288 = x3 – y3


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses