Answer:
21 h^10
Step-by-step explanation:
(7h^3)(3h^7)
Lets multiply
7*3 h^3 h^7
When the bases are the same , we add the exponents (x^a * x^b) = x ^ (a+b)
21 h^(3+7)
21 h^10
[tex]Use\ a^n\cdot a^m=a^{n+m}\\\\(7h^3)(3h^7)=(7)(h^3)(3)(h^7)=(7)(3)(h^3)(h^7)=21h^{3+7}=\boxed{21h^{10}}[/tex]