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Find x :

tan^{-1} ( x-1 ) + tan^{-1}x + tan^{-1} ( x+1 ) = tan^{-1} 3x

^{-1}(x+1+x-1 / 1-(x+1)(x-1)) = tan

^{-1}3 + tan

^{-1 }x ............when x

^{2}-1<3 and 3x<1

solve it .......and u'll get (2x/2-x

^{2}

^{ }) = (3-x/1+3x) when x lies between -√2 and 1/3

i.e. x+1(x

^{2}

^{ }-10x+6) = o when x lies b/w ......

so x = -1 neglecting x

^{2}

^{ }-10x+6 as its root does not belong to (-√2 , 1/3)