The greatest common factor of the terms 2a4b4, -3a3b5 and 4a2b5 of the expression 2a4b4 - 3a3b5 + 4a2b5 is a2b4.
Now,
2a4b4 = a2b4 2a2
-3a3b5 = a2b4 -3ab
4a2b5 = a2b4 4b
Hence, (2a4b4 - 3a3b5 + 4a2b5) can be factorised as [a2b4(2a2 - 3ab + 4b)].