7.Binomial Theorem
normal

The coefficient of $x^{13}$ in the expansion of $(1 -x)^5(1 + x + x^2 + x^3)^4$ is :-

A

$-4$

B

$0$

C

$4$

D

none of these

Solution

$(1-x)^{5} \times(1+x)^{4}\left(1+x^{2}\right)^{4}$

$=(1-x)(1-x)^{4}(1+x)^{4} \times\left(1+x^{2}\right)^{4}$

$=(1-\mathrm{x})\left(1-\mathrm{x}^{4}\right)^{4}$

$=\left(1-x^{4}\right)^{4}-x\left(1-x^{4}\right)^{4}$

Coff. of ${x^{13}}0 + {\,^4}{C_3} = 4$

Standard 11
Mathematics

Similar Questions

Start a Free Trial Now

Confusing about what to choose? Our team will schedule a demo shortly.