已知：tan(α+β)=2/5,tan(β - π/4)=1/4,那么：
tan(α + π/4)
=tan[(α+β) - (β - π/4)]
=[tan(α+β) - tan(β - π/4)]÷[1 + tan[(α+β)tan(β - π/4)]
=(2/5 - 1/4)÷(1+ 2/5 * 1/4)
=(3/20)÷(22/20)
=3/22