tan $-$1 (2x) + tan $-$1 (3x) = $\pi$/4 $\Rightarrow \,\,{{5x} \over {1 - 6{x^2}}}$ = 1 $\Rightarrow$ 6x 2 + 5x $-$ 1 = 0 x = $-$1 or x = ${1 \over 6}$ x = ${1 \over 6}$ $\because$ x > 0