A)x/x-5
<span>3/5-x=3/-(x-5)=-3/(x-5)
б)</span>
x/(x-4)^2=x/(x-4)(x-4)=(x^2+4x)/(x-4)^2(x+4)
7/x^2-16=7/(x-4)(x+4)=(7x-28)/(x-4)^2(x+4)
в)
<span>5/x+1=(5x-10)/(x+1)(x-2)
</span>
7/x-2=(7x+7)/<span>(x+1)(x-2)</span>
Пусть весь путь х
0,35x+0.4x+37.5=x 0.25x=37.5 x=150
Приводим к общему знаменателю
![\frac{1}{2} - \frac{9}{25} = \frac{1*25-9*2}{2*25} = \frac{25-18}{50} = \frac{7}{50}](https://tex.z-dn.net/?f=%20%5Cfrac%7B1%7D%7B2%7D%20-%20%5Cfrac%7B9%7D%7B25%7D%20%3D%20%20%5Cfrac%7B1%2A25-9%2A2%7D%7B2%2A25%7D%20%3D%20%5Cfrac%7B25-18%7D%7B50%7D%20%3D%20%5Cfrac%7B7%7D%7B50%7D%20%20)
Log20 120 = log20 (20 * 6) =
=log20 20 + log20 6 =
=1 + (1 / 2) * log20 (6 ^ 2) =
=1 + (1 / 2) * log20 36 =
=1 + (1 / 2) * (log20 9 + log20 4)=
=1 + (1 / 2) * (1 / (log9 20) + 2 * log20 2)
=1 + 1 / (2a) + log20 2=
=1 + 1 / (2a) + 1/(log2 20)=
=1 + 1 / (2a) + 1/(log2 10 + log2 2)=
=1 + 1 / (2a) + 1/(1/(lg 2) + 1)=
=1 + 1 / (2a) + 1 / (1 / b + 1)