EK AUR....

Let r^th termof the series be given by T_r= r/1-3r²+r⁴ then \lim_{n\rightarrow \propto \sum_{r=1}^{n}{T_{r}}} is :-

a) 3/2

b) 1/2

c) -1/2

d) -3/2

ANS :- (c)

PLEASE POST THE SOLUTION IF SOLVED....

#Mathematics #Algebra

1 Answers

r⁴-3r+1=(r²-r-1)(r²+r-1)
tr=1/2(2r/r⁴-3r+1)
=1/2({(r²+r-1)/r⁴-3r+1}-{(r²-r-1)/r⁴-3r+1})
T_r=1/2[(1/r²-r-1)-1/r²+r-1]
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n thus applting summation ans=1/2(-1)
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