Question

The power of x occurring in the 7th term in the expansion of $(\frac{4x}{5}-\frac{8}{5x}{)}^9$ is

• A. 3
• B. -3
• C. 5
• D. -5.

Answer 1

Answer: (B)

$T_7=T_{6+1}={}^9{C}_6{\left(\frac{4x}{5}\right)}^3{\left(-\frac{8}{5x}\right)}^6$
Power of $x=3-6=-3$