Express 1/(x(1-3x)) in partial fractions.

1/(x(1-3x))= A/x+ B/(1-3x) 1= A(1-3x) + B(1-3x)

when x=0    1=A

when x= 1/3     1=B/3 so B=3

1/(x(1-3x))= 1/x + 3/(1-3x)