Step-by-step explanation:
11.
[tex] \frac{x - 4}{ \frac{x}{4} - \frac{4}{x} } [/tex]
[tex] \frac{x - 4}{ \frac{ {x}^{2} }{4x} - \frac{16}{4x} } [/tex]
[tex] \frac{x - 4}{ \frac{ {x}^{2} - 16 }{4x} } [/tex]
[tex] \frac{x - 4}{ \frac{(x + 4)(x - 4)}{4x} } [/tex]
[tex] \frac{4x}{x + 4} [/tex]
12.
[tex] \frac{ \frac{ {x}^{2} - 1 }{x} }{ \frac{(x - 1) {}^{2} }{x} } [/tex]
[tex] \frac{ {x}^{3} - x}{ {x}^{3} - 2 {x}^{2} + x } [/tex]
[tex] \frac{x( {x} - 1)(x + 1) }{x( {x} - 1) {}(x - 1) } [/tex]
[tex] \frac{x + 1}{x - 1} [/tex]
13.
[tex] \frac{ \frac{ {t}^{2} }{ \sqrt{ {t}^{2} + 1} } - \sqrt{ {t}^{2} + 1} }{ {t}^{2} } [/tex]
[tex] \frac{ \frac{ {t}^{2} }{ \sqrt{ {t}^{2} + 1 } } - \frac{ {t}^{2} + 1}{ \sqrt{ {t}^{2} + 1 } } }{ {t}^{2} } [/tex]
[tex] \frac{ \frac{1}{ \sqrt{ {t}^{2} + 1 } } }{ {t}^{2} } [/tex]
[tex] \frac{ - \frac{ \sqrt{ {t}^{2} + 1 } }{ {t}^{2} + 1 } }{ {t}^{2} } [/tex]
[tex] - \frac{ \sqrt{ {t}^{2} + 1} }{ {t}^{2}( {t}^{2} + 1) } [/tex]
14.
[tex] \frac{3x { }^{ \frac{1}{3} } - x {}^{ \frac{ - 2}{3} } }{3x {}^{ - \frac{2}{3} } } [/tex]
[tex] \frac{3x - 1}{3} [/tex]
