সাধারণ পদ , মধ্যপদ ও সমদূরবর্তী পদ নির্ণয়

The term independent of x in the expansion of (x14)4(x+1x)3\displaystyle \left ( x -\dfrac{1}{4} \right )^4\left ( x + \dfrac{1}{x} \right )^3

হানি নাটস

(x1x)4(x+1x)3=(x1x)(x1x)3(x+1x)3=(x1x){(x1x)(x+1x)}3=(x1x)(x21x2)3=(x1x)(x61x63x4×1x2+3x2×1x4)=(x1x)(x61x63x2+3x2)=x71x53x3+3xx5+1x7+3x3x3+0 \begin{aligned} & \left(x-\frac{1}{x}\right)^{4}\left(x+\frac{1}{x}\right)^{3} \\ = & \left(x-\frac{1}{x}\right)\left(x-\frac{1}{x}\right)^{3}\left(x+\frac{1}{x}\right)^{3} \\ = & \left(x-\frac{1}{x}\right)\left\{\left(x-\frac{1}{x}\right)\left(x+\frac{1}{x}\right)\right\}^{3} \\ = & \left(x-\frac{1}{x}\right)\left(x^{2}-\frac{1}{x^{2}}\right)^{3} \\ = & \left(x-\frac{1}{x}\right)\left(x^{6}-\frac{1}{x^{6}}-3 x^{4} \times \frac{1}{x^{2}}+3 x^{2} \times \frac{1}{x^{4}}\right) \\ = & \left(x-\frac{1}{x}\right)\left(x^{6}-\frac{1}{x^{6}}-3 x^{2}+\frac{3}{x^{2}}\right) \\ = & x^{7}-\frac{1}{x^{5}}-3 x^{3}+\frac{3}{x}-x^{5}+\frac{1}{x^{7}}+3 x-\frac{3}{x^{3}}+0 \end{aligned}

\Rightarrow Term independent of x=0 x=0

Hence the correct option is B.

সাধারণ পদ , মধ্যপদ ও সমদূরবর্তী পদ নির্ণয় টপিকের ওপরে পরীক্ষা দাও