Question

2arctg1+3arctg(-1÷√3)

Answer 1

$2arctg1+3arctg(-frac{1}{sqrt{3}})=2arctg1-3arctgfrac{sqrt{3}}{3}=\=2*frac{pi}{4}-3*frac{pi}{6}=frac{pi}{2}-frac{pi}{2}=0$