Simplify $\left(5\cdot7^3\right)^4$(5·73)4, leaving your answer in exponential form.
Simplify $\left(3^2\cdot5^4\right)^2$(32·54)2, leaving your answer in exponential form.
Simplify $\left(13\cdot7^2\right)^4$(13·72)4, leaving your answer in exponential form.
Simplify $\left(5^6\cdot7^8\right)^6$(56·78)6, leaving your answer in exponential form.