Solve this plz

This is the first answer.

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Thanx
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2nd part ans

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x2+1/x2=7
x2+1/x2+2=7+2                        (adding 2 on both the sides)
x2+1/x2+2=9
(x+1/x)2=32
x+1/x=3
(x+1/x)3=x3+1/x3+3(x+1/x)=33
x3+1/x3+3(3)=27
x3+1/x3=27-9
x3+1/x3=18
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x+1/x=7
(x+1/x)3=73
x3+1/x3+3(x+1/x)=27
x3+1/x3+3(3)=27
x3+1/x3+9=27
x3+1/x3=18
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The first answer is here

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This is the third one...

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1. We know that (a + b + c)2 = a2 + b2 + c2 + 2ab + 2bc + 2ac
                                         = 280 + 2(ab + bc + ac)
                                         = 280 + 2(9/2)
                                         = 280 + 9
                                         = 289
Therefore (a + b + c)2 = 289
Therefore a + b + c = 17
Therefore (a + b + c)3 = 173
                                   = 4913.
 
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