`#Chae`
`a)`
`4^4 . 4^5 =` `4^{4 + 5}` `=` `4^9`
`27 . 3^5 = 3^3 . 3^5 = 3^{3 + 5} = 3^8`
`32 . 64 = 2^5 . 2^6 = 2^{5 + 6} = 2^11`
`b)`
`9^8 . 9 = 9^8 . 9^1 = 9^{8 + 1} = 9^9`
`128 . 2^4 = 2^7 . 2^4 = 2^{7 + 4} = 2^11`
`3^9 : 243 = 3^9 : 3^5 = 3^{9 - 5} = 3^4`
`c)`
`3 . 12^6 . 4 . 12^3 = 12 . 12^6 . 12^3 = 12^{6 + 3 + 1} = 12^10`
`15^6 . 3 . 15^3 . 5 = 15^6 . 15 . 15^3 = 15^{6 + 1 + 3} = 15^10`
`21^3 . 7 . 21^4 . 3 = 21^3 . 21 . 21^4 = 21^{3 + 1 + 4} = 21^8`
`⇒ a = a^1`