5/(х-7)-2/х-3х/х 2-49+21/49-х 2 выражение

5/(x-7) - 2/x  -  3x/(x² -49) +21/(49-x²) =
= 5/(x-7) -  2/x  -  [3x/(x-7)(x+7)] - [21/(x-7)(x+7) ]=
= (5x(x+7) - 2(x²-49)  - 3x² -21x)   /   (x(x-7)(x+7) )  =
= (5x²+35x -2x² +98 -3x² -21x) /  (x(x-7)(x+7) )=
= (14x +98) / x(x-7)(x+7) =
= 14(x+7) /  x(x-7)(x+7) =
= 14 / x(x-7)