x^2+1/x^2=7,then find x^3+1/x^3
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(x+1/x)^2 = x^2+1/x^2+2
(x+1/x)^2=7+2=9
x+1/x = 3
(x+1/x)^3 = x^3+1/x^3+3*x*1/x(x+1/x)
27-9 = x^3 + 1/x^3 = 18
Sreekar273:
Get the answer of (x+1/x) then cube it to get the answer
in detail
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x + 1/x)2 = x2 + 1/x2 + 2
(x + 1/x)2 = 9
x + 1/x = 3
now
(x + 1/x)3 = x3 + 1/x3 + 3(x + 1/x)
27 = x3 + 1/x3 + 9
or
x3 + 1/x3 = 27 - 9 = 18
it should be the answer...
I hope it help's u....
(x + 1/x)2 = 9
x + 1/x = 3
now
(x + 1/x)3 = x3 + 1/x3 + 3(x + 1/x)
27 = x3 + 1/x3 + 9
or
x3 + 1/x3 = 27 - 9 = 18
it should be the answer...
I hope it help's u....
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