Terms for subject Mathematics containing it is well known

English	Russian
it is well known	хорошо известно
it is well known	хорошо известно, что (, that for sufficiently small ...)
it is well known	общеизвестно
it is well known that the foregoing numerical representation	хорошо известно, что следующее численное представление (it is well known that the foregoing numerical representation of the extended Cartesian plane does represent a consistent system)
it is well known that the foregoing numerical representation of the extended Cartesian plane does represent a consistent system	непротиворечивая система уравнений