Answers

2015-05-26T20:06:22+05:30
X + 1/x = 5 
now 
x³ + 1/x³
= (x + 1/x )³ - 3x/x.(x+1/x)
= 5³ - 3×5
= 125-3×5
= 110
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Answer is not 122 because it is not there in given options
Sorry my mistake will you keep - in + places in the question and solve it again
x³ + 1/x³
= (x + 1/x )³ - 3x/x(x+1/x)= 5³ - 3*5
= 125-3*5
= 110
i think this is correct
yes
2015-05-26T20:46:32+05:30
At first , note that, x^3+x^-3=(x+1/x)^3-3*(x+1/x). now put the values.
125-3*5=110

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