Answer:
a²⁸b¹⁴
Step-by-step explanation:
[tex]\text{Use}\\\\(ab)^n=a^nb^n\\\\\bigg(a^n\bigg)^m=a^{nm}\\\\a^n\cdot a^m=a^{n+m}\\--------------------\\\\\bigg(a^3b\bigg)^7\bigg(a^7b^7\bigg)=\bigg(a^3\bigg)^7(b^7)(a^7)(b^7)=(a^{3\cdot7})(a^7)(b^7)(b^7)\\\\=\bigg(a^{21+7}\bigg)\bigg(b^{7+7}\bigg)=\boxed{a^{28}b^{14}}[/tex]
