SOLUTION: what is the seventh term of the expansion (2a-3b) to the ninth power?

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Question 20942: what is the seventh term of the expansion (2a-3b) to the ninth power?
Answer by venugopalramana(3286) About Me  (Show Source):
You can put this solution on YOUR website!
7 TH TERM OF (2A-3B)^9
AS PER BINOMIAL THEOREM R+1 ST. TERM Tr+1 OF EXPANSION (X+A)^N IS GIVEN BY
Tr+1=nCr*{X^(N-R)}*(A^R) ..WE WANT 7TH.TERM HENCE R=6...SO
T7=9C6*{(2A)^(9-6)}*(3B)^6
=9C6*8*A^3*3^6*B^6
=(9!/6!*3!)*8*A^3*3^6*B^6