Question

The $4th$ term from the end in the expansion of ${(\frac{x^3}{2}-\frac{2}{x^2})}^7$ is

• A. $35x$
• B. $70x^2$
• C. $35x^2$
• D. $70x$

Answer 1

The correct option is D $70x$

For the above question
$T_{r+1}={}^7{C}_r{x}^{21-5r}{2}^{2r-7}$
For the fourth term, from the end $r=4$
$T_{5+1}={}^7{C}_4{x}^1{2}^{}$
$=\left(35\right)\left(2\right)x$
$=70x$