In polynomials, there's a solved example of the problem
(2 x + 5 y ) 3 − (2 x − 5 y ) 3
I have not understood the alternative (shorter) method. Could you please explain each step in detail? The link of the problem is given below:
http://cbse.meritnation.com/cbse-math-math/polynomials/7/99/studymaterials.html
We will be able to offer you meaningful help only if you can clearly write down the specific problem areas/ topics in a given lesson. We look forward to hear from you again!