\(\left(3×4\right)^4×\left(4×3\right)^5=12^4×12^5=12^9=5159780352\)
\(\left(3.4\right)^4.\left(4.3\right)^5\)
\(\Rightarrow3^4.4^4.4^5.3^5\)
\(\Rightarrow\left(3^4.3^5\right).\left(4^4.4^5\right)\)
\(\Rightarrow3^9.4^9\)
\(\Rightarrow\left(3.4\right)^9\)
(3.4)^4 . (4.3)^5 = 3^4 . 4^4 . 4^5 . 3^5 = 3^9 . 4^9 = (3.4)^9 = 12^9.