Express 1/(1+2x)(1-x) in partial fractions

1/(1+2x)(1-x)=(A/(1+2x))+(B/(1-x))1=A(1-x)+B(1+2x) Now set the bracket of one of A or B equal to 0 to get an equation with 1 unknown.Set x=11=A(1-1)+B(1+2(1))1=A(0)+B(3)1=3BB=1/3Set x=-(1/2)1=A(1-(-1/2))+B(1+2(-1/2))1=A(3/2)+B(0)1=A(3/2)A=2/3(2/3(1+2x)) + (1/3(1-x))