Question

!!!!!15б!!!срочно!!!!!
1)Докажите тождество:

Answer 1

$frac{2}{(b-c)(c-a)} - frac{2}{(a-b)(c-b)} + frac{2}{(a-c)(b-a)} =0 \ \ frac{2}{(b-c)*-(a-c)} - frac{2}{(a-b)*-(b-c)} + frac{2}{(a-c)*-(a-b)}= 0\ \ - frac{2}{(b-c)(a-c)} + frac{2}{(a-b)(b-c)} - frac{2}{(a-c)(a-b)} =0 \ \ frac{-2(a-b)+2(a-c) -2(b-c)}{(a-b)(b-c)(a-c)} =0 \ \ frac{-2a+2b+2a-2c-2b+2c}{(a-b)(b-c)(a-c)} =0 \ \ frac{(-2a+2a)+(2b-2b) + (-2c+2c)}{(a-b)(b-c)(a-c)} =0 \ \ frac{0}{(a-b)(b-c)(a-c)} =0 \ \ 0=0$


$frac{1}{x} + frac{1}{a} =b \ \ frac{1}{x} =b - frac{1}{a} \ \ frac{1}{x} = frac{ab-1}{a} \ \ x * (ab-1) = a*1 \ \ x * (ab-1) = a \ \ x= frac{a}{ab-1}$