Question

Помогите Вычислить
(2(√3-√7))/((5-√21)*(√7+√3))

Answer 1

2(√3-√7)(√3-√7)/[(5-√21)(√7+√3)(√3-√7)]=
=2(3-2√21+7)/[)5-√21)(3-7)]=2(10-2√21)/[-4(5-√21)]
=4(5-√21)/[-4(5-√21)]=-1