Precalculus, Chapter 5, 5.3, Section 5.3, Problem 21

tan(3x)tan(x-1)=0
solving each part,
tan(3x)=0
General solutions for tan(3x)=0 are,
3x=0+pin
x=(pin)/3
General solutions for tan(x-1)=0 are,
x-1=0+pin
x=1+pin
so the solutions are,
x=(pin)/3 , x=pin+1