If x2 - 3x + 1= 0  and x > 1, then the value of x3 + \(\frac{1}{x^3}\) will be:

16 18 20 22

18

If x2 - 3x + 1= 0 Divide by x on both sides, x +  \(\frac{1}{x}\) = 3 x3 + \(\frac{1}{x^3}\)  = 33 - 3 × 3 = 18   Note - if x +  \(\frac{1}{x}\) = a then x3 + \(\frac{1}{x^3}\) =  a3 - 3a