8a4b+1/125ab4

Factorise it

Step-by-step explanation:

First pull out the common factor of ab

ab (8a^3 + (1/125) b^3)

This is basically the sum of cubes. The linear factor is

(2a + 1/5 b)

The other factor is these two factors squared and their multiplicand subtracted.

(2a^2 - 2/5 ab + 1/25b^2)

Now put all this together and you get

ab (2a + 1/5 b) ((2a^2 - 2/5 ab + 1/25b^2)