Answer:
Step-by-step explanation:
[tex](\frac{a^{4}}{-7b^{3}})^{2}=\frac{(a^{4})^{2}}{(-7b^{3})^[2}}\\\\=\frac{a^{4*2}}{(-7)^{2}b^{3*2}}\\\\=\frac{a^{8}}{49b^{6}}[/tex]