Show that the first three terms, in descending powers of xxx, of the expansion of (3x−2)8(3x - 2)^8(3x−2)8 are given by 6561x8+ax7+bx66561x^8 + ax^7 + bx^66561x8+ax7+bx6 where aaa and bbb are integers to be found.
Find the constant term in the expansion of (3x−2x)8\left(3x - \frac{2}{x}\right)^8(3x−x2)8