MCQ
${d \over {dx}}{\tan ^{ - 1}}\left( {{{ax - b} \over {bx + a}}} \right) = $
- A${1 \over {1 + {x^2}}} - {{{a^2}} \over {{a^2} + {b^2}}}$
- B${{ - 1} \over {1 + {x^2}}} - {{{a^2}} \over {{a^2} + {b^2}}}$
- C${1 \over {1 + {x^2}}} + {{{a^2}} \over {{a^2} + {b^2}}}$
- ✓None of these