+128406
(x-4/x)^7
Here's the expansion
x^7 - 16384/x^7 - 28 x^5 + 28672/x^5 + 336 x^3 - 21504/x^3 - 2240 x + 8960/x
The coefficient on the x term is -2240
It is determined thusly :
C (7, 3) * ( x)^4 * (- 4/ x)^3 = 35 * x^4 * (-4)^3 / x^3 = (35) *( - 64) * x^4 / x^3 = ( -2240 ) x
