Lim x→4 3 - √x² - 7 / x² - 2x - 8 =......

[tex] \\ = \frac{3 - \sqrt{ {x}^{2} - 7} }{ {x}^{2} - 2x - 8 } . \frac{3 + \sqrt{ {x}^{2} - 7} }{ 3 + \sqrt{ {x}^{2} - 7} }\\ = \frac{9 - ( {x}^{2} - 7) }{(x - 4)(x + 2)(3 + \sqrt{ {x}^{2} - 7) } } \\ = \frac{ - {x}^{2} + 16}{(x - 4)(x + 2)(3 + \sqrt{ {x}^{2} - 7) } } \\ = \frac{( - x - 4)(x - 4)}{(x - 4)(x + 2)(3 + \sqrt{ {x}^{2} - 7)} } \\ = \frac{ - x - 4}{(x + 2)( x + \sqrt{ {x}^{2} - 7)} } \\ = \frac{ - 4 - 4 }{(4 + 2)(4 + \sqrt{ {4}^{2} - 7) } } \\ = \frac{ - 8}{6(4 + 3)} \\ = \frac{ - 8}{42} \\ = - \frac{4}{21} [/tex]
ikuti yah