Which equations are correct?

We are  using  the property that

ax^m  *  bxⁿ    =   (a*b)  (x^m * xⁿ)  =  (a*b) (x^m+n )

So...for instance  .....  3x³ (7x²)  =  (3*7) (x³⁺²)  =  21x⁵

So......the last three are correct