If $x^{2} + 6x+ 1 = 0$, then the value of $\left(x + 6\right)^{3} + \frac{1}{\left(x + 6\right)^{3}}$ = ?
Answer & explanation
Correct answer: option 4
If x + \(\frac{1}{x}\) = n
then, $x^3 +\frac{1}{x^3}$ = n3 - 3 × n
If $x^{2} + 6x+ 1 = 0$
Find $\left(x + 6\right)^{3} + \frac{1}{\left(x + 6\right)^{3}}$
Let x + 6 = t
x = t - 6
Put the value of x in $x^{2} + 6x+ 1 = 0$
$(t-6)^{2} + 6(t-2)+ 1 = 0$
= t2 + 36 - 12t + 6t - 12 + 1 = 0
= t2 - 6t + 25 = 0
= t(t-6) + 25 = 0
= t ×