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Answer 1 · 2017-11-26T12:18:44

Fifth term is #560x^3#

#(x+2)^7 ; t_5 = ?#

We know #(a+b)^n= nC_0 a^n*b^0 +nC_1 a^(n-1)*b^1 + nC_2 a^(n-2)*b^2+..........+nC_n a^(n-n)*b^n#

Here #a=x,b=2,n=7# We know, #nC_r = (n!)/(r!*(n-r)!#
#:.7C_4 =(7!)/(4!*3!)=35 #

#t_5= nC_4*x^(n-4)*2^4#

#t_5= 35*x^(7-4)*2^4=560x^3 #

Fifth term is #560x^3# [Ans]

Answer 2 · 2017-11-26T12:55:07

#560x^3#

Refer to the file attached for an explanation.

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