Originally Posted by

**offahengaway and chips** Hi,

im working through a worked example from a text, I have got to the point where I am cancelling the indicies. The text has missed out the cancelling process and I cant see how they have done it, any tips would be appreciated.

{7^2n-7^n-1.(-5)^n+1-(-5)^n-1.7^n+1 +(-5)^2n} **- **{7^2n -2(7^n(-5)^n)+(-5)^2n}

After cancelling this we get( this is the bit im having trouble with)

7^n-1(-5)^n-1 x {-(-5)^2 - 7^2 + 2 x 7 x (-5)}

Any hints would be greatly apreciated

p.s not sure if i have posted this in the right part of the forum

thanks