∴tan a+ tan b=-3/2

tan a tan b=-7/2

tan(a+b)=(tan a+tan b)/( 1-tan a tan b)=- 1/3

2 . tan2a = tan(a+b+a-b)= tan(a+b)+tan(a-b)/ 1-tan(a+b)tan(a-b)=-4/7

tan2b = tan(a+b-(a-b))= tan(a+b)-tan(a-b)/ 1+tan(a+b)tan(a-b)=- 1/8