- Home
- Standard 11
- Mathematics
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