Question

If x + 1/x = 4 then what is x^3 + 1/x^3 = ?

Answer 1

52

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1) x+1/x=4
x^3+1/x^3=?
(x+1/x)^3= 4^3=64
x^3+1/x^3+3*x*1/x*(x+1/x)=64 considering 1)
x^3+1/x^3+3*4=64
x^3+1/x^3=62-12=52