• Answer of this question

    Solve the equation tan^-1 (x-1/x-2 ) tan^-1 (2x-1/2x 1) = tan^-1 23/
    Nischal Dasari's image
    Nischal Dasari

    Answer:

    x = -3/8  & x = 4/3

    Step-by-step explanation:

    Tan⁻¹(x-1/x+1)+Tan⁻¹(2x-1/2x+1)=Tan⁻¹(23/36)

     

    Let say Tan⁻¹((x-1)/(x+1)) = a  => Tan a = (x-1)/(x+1)

    Tan⁻¹((2x-1)/(2x+1)) = b  => Tan b = (2x-1)/(2x+1)

    => a + b = Tan⁻¹(23/36)  - eq 1

     

    Using formula

    Tan ( a + b) = (Tan a + Tan b )/( 1 - Tan a . Tan b)

     

    => Tan  ( a + b) = ((x-1)/(x+1) + (2x-1)/(2x+1)) / ( 1  - ((x-1)/(x+1))((2x-1)/(2x+1) )

    => Tan  ( a + b) =( (x-1)(2x+1) + (2x-1)(x+1) ) / ( (2x+1)(x+1) - (2x-1)(x-1) )

    => Tan  ( a + b) = (2x² -x -1 + 2x² + x  - 1) / ( 2x² + 3x + 1 - (2x² -3x + 1) )

    => Tan  ( a + b) = (4x² - 2)/6x

    => Tan  ( a + b) = (2x² - 1)/3x

    => a + b = Tan⁻¹((2x² - 1)/3x)

    Equating with eq 1

    => Tan⁻¹((2x² - 1)/3x) = Tan⁻¹(23/26)

    => (2x² - 1)/3x = 23/36

    =>  (2x² - 1) = 23x/12

    => 24x² - 12 = 23x

    => 24x² - 23x - 12 = 0

    => 24x² -32x + 9x - 12 = 0

    => 8x(3x - 4) + 3(3x -4) = 0

    => (8x +3)(3x -4) = 0

    => x = -3/8  & x = 4/3


    Written on April 3, 2021, 10:47 a.m.