What is the coefficient of x11 in the expansion of (x3 - 2/x2 )12 ?
( x3 - 2/x2 )12= it is in the form (x -a)n
therefore put x value as x 3 and the value of a is -2/x2 i.e., -2/x2 can be written as -2x-2 and n= 12
so Tr+1= ncr . xn-r .ar
= 12Cr . (x3)12-r . (-2x-2)r
=12Cr . x(36-3r). -2r . x-2r
= 12Cr .-2r . x (36-3r-2r) ------- (1)
put x= 11 so,
36-3r-2r=11
36-11=5r
25=5r
5=r
put the value of r in equation (1)
so v get Tr+1 = 12Cr. -2r . x (36-5r)
T5+1=12C5 . -25 . x11
T6=12C5 .-25 THIS IS THE COEFFICIENT OF X11
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