$$ 4+\frac{1}{4+\frac{1}{4+\frac{1}{4+\ldots \infty}}}= $$

If $x^2+5 a x+6=0$ and $x^2+3 a x+2=0$ have a common root, then that common root is

If $\alpha, \beta, \gamma$ are roots of equations $x^3+a x^2+b x+x=0$, then $\alpha^{-1}+\beta^{-1}+\gamma^{-1}=$

For all positive integers $ n $ if $ 3^{2n+1} + 2^{n+1} $ is divisible by $ k $, then the number of prime numbers less than or equal to $ k $ is