Q31 of 70 Page 371

Show that the term containing x3 does not exist in the expansion of .

For ,


a=3x, and n=8


We have a formula,







To get coefficient of x3 we must have,


(x)8-2r = (x)3


• 8 - 2r = 3


• 2r = 5


• r = 2.5


As is not possible


Therefore, the term containing x3 does not exist in the expansion of


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