Although the question's print is not clear, to the best of my knowledge, as I can see, We are given that:
[tex] r(x)=-x^5 [/tex] and [tex] s(x)=2x^3 [/tex]
No, we know that, by definition:
[tex] (r.s)(x)=r(x)\times s(x) [/tex]
[tex] \therefore (r.s)(x)=-x^5\times 2x^3=-2x^8 [/tex]
Thus, for the functions r and s which are defined for all real numbers x, the answer to the question asked is:
[tex] (r.s)(x)=-2x^8 [/tex]