alleryThe term independent of $x$ in the expansion of $\left(x+\dfrac{1}{x}\right)^6$ is:
A1
B20
C6
D15
Answer & Solution
Correct answer: B. 20
T_{r+1}=C(6,r)x^{6−r}x^{−r}=C(6,r)x^{6−2r}; independent of x ⟹ 6−2r=0 ⟹ r=3; C(6,3)=20.
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