Question

if x^2+1/x2=7 then find the value of x^3+1/x3

Answer 1

(x + 1/x) = x + 1/x + 2

(x + 1/x) = 9  

x + 1/x = 3  

then,

(x + 1/x) = x + 1/x + 3(x + 1/x)

27 = x + 1/x + 9

Answer 2

(x + 1/x) = x + 1/x + 2 (x + 1/x) = 9 x + 1/x = 3 now (x + 1/x) = x + 1/x + 3(x + 1/ x) 27 = x + 1/x + 9 or x + 1/x = 27 - 9 = 18

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