[JEE Main 2011] the coefficient of x 7 in 1 x x 2 x 3 6 is
The coefficient of $x^7$ in $(1-x-x^2+x^3)^6$ is
(a) $-132$
(b) $-144$
(c) $132$
(d) $144$
1 Answer
VAVidaara Admin
✓ Vidaara Team
✓ Accepted
· 2d ago
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Correct answer: (b) $-144$
$(1-x-x^2+x^3)^6=(1-x)^{12}(1+x)^6$; the coefficient of $x^7$ works out to $-144$.
JEE Main 2011 · Binomial Theorem — verified solution by the Vidaara Team.
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