Answer:
[tex]\large\boxed{(6r-1)(-8r^3)=-48r^4+8r^3}[/tex]
Step-by-step explanation:
[tex](6r-1)(-8r^3)\qquad\text{use the distributive property}\ a(b+c)=ab+ac\\\\=(6r)(-8r^3)+(-1)(-8r^3)\qquad\text{use}\ (a^n)(a^m)=a^{n+m}\\\\=-48r^{1+3}+8r^3\\\\=-48r^4+8r^3[/tex]
