81/9*21*21-9/-21=1/49+3/7=22/49
N!=(n-1)!*n (напрмер 3!=2!*3)
(n+1)!=(n-1)!*n*(n+1)
тогда левая часть равенства:
(n-1)! +(n-1)!*n+(n-1)!*n*(n+1)=выносим (n-1)факториал за скобки
=(n-1)!*(1+n+n(n+1))=(n-1)!*(1+n+n²+n)=(n-1)!*(n²+2n+1)=(n-1)!*(n+1)²
1.log2(5)/4
2.x=\sqrt{17} [/tex]
![g( x^{2} -4) = \frac{1}{ x^{2} -4}\\\\f(x+2)= \frac{2}{x+2}\\\\ \frac{1}{ x^{2} -4}- \frac{2}{x+2} =-1\\\\ \frac{1}{(x-2)(x+2)}- \frac{2}{x+2}+1=0\\\\ \frac{1-2x+4+ x^{2} -4}{ x^{2} -4} =0\\\\ \frac{ x^{2} -2x+1}{ x^{2} -4}=0](https://tex.z-dn.net/?f=g%28+x%5E%7B2%7D+-4%29+%3D++%5Cfrac%7B1%7D%7B+x%5E%7B2%7D+-4%7D%5C%5C%5C%5Cf%28x%2B2%29%3D+%5Cfrac%7B2%7D%7Bx%2B2%7D%5C%5C%5C%5C+%5Cfrac%7B1%7D%7B+x%5E%7B2%7D+-4%7D-+%5Cfrac%7B2%7D%7Bx%2B2%7D+%3D-1%5C%5C%5C%5C+%5Cfrac%7B1%7D%7B%28x-2%29%28x%2B2%29%7D-+%5Cfrac%7B2%7D%7Bx%2B2%7D%2B1%3D0%5C%5C%5C%5C+%5Cfrac%7B1-2x%2B4%2B+x%5E%7B2%7D+-4%7D%7B+x%5E%7B2%7D+-4%7D+%3D0%5C%5C%5C%5C+%5Cfrac%7B+x%5E%7B2%7D+-2x%2B1%7D%7B+x%5E%7B2%7D+-4%7D%3D0++++++)
x² - 2x + 1 = 0 x ≠ 2 x ≠ - 2
(x - 1)² = 0
x = 1