Inthe expansion of \[(1+x+{{x}^{2}}){{e}^{-x}}\],the coefficient of\[{ – McqOptions

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1.	Inthe expansion of \[(1+x+{{x}^{2}}){{e}^{-x}}\],the coefficient of\[{{x}^{2}}\] is
A.	1
B.	\[-1\]
C.	1/2
D.	-1/2
Answer» D. -1/2

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