7.Binomial Theorem
hard

यदि $\left(x+x^{\log _{2} x}\right)^{7}$ के प्रसार में चौथा पद $4480$ है, तो $x ( x \in N )$ का मान है

A

$2$

B

$4$

C

$3$

D

$1$

(JEE MAIN-2021)

Solution

${ }^{7} C _{3} x ^{4} x ^{\left(3 \log _{2}^{x}\right)}=4480$

$\Rightarrow x ^{\left(4+3 \log _{2}^{x}\right)}=2^{7}$

$\Rightarrow \quad(4+3 t ) t =7 ; t =\log _{2} x$

$\Rightarrow t =1, \frac{-7}{3} \Rightarrow x =2$

Standard 11
Mathematics

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