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Q.
Maximum sum of coefficient in the expansion of $\left(1-x \sin \theta+x^{2}\right)^{ n }$ is
Binomial Theorem
Solution:
Sum of coefficients in $\left(1-x \sin \theta+x^{2}\right)^{n}$ is
$(1-\sin \theta+1)^{ n }$
(Putting $x=1$ )
This sum is greatest when $\sin \theta $
$=-1$, then maximum sum is $3^{ n }$.