If $x + \frac{1}{3x} = 5, $ then the value of $27x^3 +\frac{1}{x^3}$ will be :

3240

If $x + \frac{1}{3x} = 5, $

then the value of $27x^3 +\frac{1}{x^3}$ will be = ?

If $K+\frac{1}{K}=n$

then, $K^3+\frac{1}{K^3}$ = n³ – 3 × k × \(\frac{1}{k}\)

If $x + \frac{1}{3x} = 5, $

Then $x^3 +\frac{1}{27x^3}$ = 5³ – 3 × 5 ÷ 3 = 120

Multiply the whole equation by 27 to get the desired form of equation,

and the value of $27x^3 +\frac{1}{x^3}$ = 120 × 27 = 3240