What is the degree of the polynomial P(x)?

 $P\left(x\right)=3x^4-6x^2+x-9$  

What is the leading coefficient of the polynomial P(x)?

 $P\left(x\right)=3x^4-6x^2+x-9$  

The polynomial  $P\left(x\right)$  has degree 2. What is the degree of  $\left(P\left(x\right)\right)^3$  ?