Rút gọn biểu thức sau
(3\ +\ \frac{\frac{9}{2}}{\sqrt5}\ )\times\ ( 2-\sqrt5 )n + (3\ -\ \frac{\frac{9}{2}}{\sqrt5}) \times(2+\sqrt5 )

Respuesta :

Answer:

Step-by-step explanation:

[tex]\left(3+\frac{\frac{9}{2}}{\sqrt{5}}\right)\left(2-\sqrt{5}\right)n+\left(3-\frac{\frac{9}{2}}{\sqrt{5}}\right)\left(2+\sqrt{5}\right)[/tex]

[tex]\mathrm{Apply\:the\:fraction\:rule}:\quad \frac{\frac{b}{c}}{a}=\frac{b}{c\:\times \:a}[/tex]

[tex]=\left(\frac{9}{2\sqrt{5}}+3\right)\left(2-\sqrt{5}\right)n+\left(-\frac{\frac{9}{2}}{\sqrt{5}}+3\right)\left(2+\sqrt{5}\right)[/tex]

[tex]\mathrm{Apply\:the\:fraction\:rule}:\quad \frac{\frac{b}{c}}{a}=\frac{b}{c\:\times \:a}[/tex]

[tex]=\left(\frac{9}{2\sqrt{5}}+3\right)\left(2-\sqrt{5}\right)n+\left(-\frac{9}{2\sqrt{5}}+3\right)\left(2+\sqrt{5}\right)[/tex]

[tex]=\frac{-12-9\sqrt{5}}{2\sqrt{5}}n+6n+\left(3-\frac{9}{2\sqrt{5}}\right)\left(2+\sqrt{5}\right)[/tex]

[tex]=\frac{-12-9\sqrt{5}}{2\sqrt{5}}n+6n+\frac{12-9\sqrt{5}}{2\sqrt{5}}+6[/tex]

[tex]=\frac{\sqrt{5}\left(\left(3\sqrt{5}-12\right)n+12-9\sqrt{5}\right)}{10}+6[/tex]