What is the Coefficient of the 8th Term of the Expansion of (2x - 1/x)^10?

From the given

a = 2x	r = 8
b = 1/x	m = r - 1 = 7
n = 10

 

$r^\text{th} ~ \text{term} = (nCm)(a^{n - m})(b^m)$

$8^\text{th} ~ \text{term} = (10C7)(2x)^{10 - 7} \cdot \left( -\dfrac{1}{x} \right)^7$

$8^\text{th} ~ \text{term} = (120)(2^3)(-1)^7 \cdot \dfrac{x^3}{x^7}$

$8^\text{th} ~ \text{term} = -\dfrac{960}{x^4}$
 

Coefficient of the 8^th term = -960   ←   answer