用解二次方程的方法解方程 超急!!!!

1)1/(x+1) + 1/(x-1) = 3/4(x+1)(x-1) [1/(x+1) + 1/(x-1)] = (3/4) (x+1)(x-1)(x-1) + (x+1) = (3/4) (x+1)(x-1)8x = 3 (x+1)(x-1)8x = 3(x² - 1)3x² - 8x - 3 = 0(3x + 1)(x - 3) = 0x = - 1/3 或 x = 3 2)2tanθ = cosθ2sinθ /cosθ = cosθ2sinθ = cos² θ 2sinθ = 1 - sin² θsin² θ + 2sinθ - 1 = 0sinθ = - 1 + √2 or - 1 - √2 (捨去因 -1 ≤ sinθ ≤ 1)θ = 24.4698° , 155.5302° , 其中0° ≤ θ ≤ 360°