Terms for subject Mathematics containing it is in order

English	Russian
in order to prove this lemma, it is necessary to put impose some restrictions on f	ограничение на
in order to take the square root of a complex number, it is reasonable to convert this number into trigonometric form	для извлечения квадратного корня из комплексного числа таковое целесообразно перевести в тригонометрическую форму
it is in order	уместно