5
3^4*5^6*4^4/(8^2*15^4)=3^4*5^6*2^8/(2^6*3^4*5^4)=5^2*2^2=10^2=100
6
4a³b-2ab³+3a+2a³b+2ab³-a=6a³b+2a
4a³b-2ab³+3a-2a³b-2ab³+a=2a³b-4ab³+4a
7
(a²+2ab+4b²)(a-2b)=a³-(2b)³=a³-8b³
(5a^4b-40ab^4)/5ab=5ab(a³-8b³)/5ab=a³-8b³
a³-8b³=a³-8b³
8
x³+x²-2x³+3x-4x+6-x³+x²=0
-x+6=0
x=6