Formula use: \left(a-b\right)^3=a^3-b^3-3.a.b.\left(a-b\right)

Explanation

Here, given expression is :
\left(3x-2y\right)^3-\left(2x-y\right)^3-3(3x-2y)(2x–y) (x–y)
Let,
\left(3x-2y\right)=a
\left(2x-y\right)=b
Now,
\left(a-b\right)
\rightarrow\{\left(3x-2y\right)-\left(2x-y\right)\}
\rightarrow\left(3x-2y-2x+y\right)
\therefore\left(x-y\right)
So, \left(3x-2y\right)^3-\left(2x-y\right)^3-3.\left(3x-2y\right).\left(2x-y\right).\{\left(3x-2y\right)-\left(2x-y\right)\}
\rightarrow a^3-b^3-3.a.b\left(a-b\right)
\rightarrow\left(a-b\right)^3
Put the value of \left(a-b\right), we get :
\left(a-b\right)^3
\rightarrow\left(x-y\right)^3
\therefore x^3-3x^2y+3xy^3-y^3
Ans: x^3-3x^2y+3xy^2-y^3\ .