How do you find the fourth term of ((2x-z)^2 )^6((2xz)2)6?

1 Answer
May 27, 2015

((2x-z)^2)^6 = (2x-z)^12((2xz)2)6=(2xz)12

The fourth term of this expansion is
color(red)(12C4) * (2x)^4 * (-z)^(12-4)12C4(2x)4(z)124

= (12!)/((4!)(8!)) * 16x^4 * z^8=12!(4!)(8!)16x4z8

= (495) *16x^4z^8=(495)16x4z8

=7920x^4z^8=7920x4z8

color(red)("Note")Note
I'm not certain of the current notation standard for this expression: "12 Choose 4" and have used the form I learned more than 50 years ago.