(√7/√7+√27-√3/√7-√27) * (1-2√21) сроооочно !!!!!

((√7(√7-√27)-√3(√7+√27))/(7-27))*(1-2√21)=((7-3√21-√21-9)/(-20))*(1-2√21)=(-(2+4√21)/(-20))*(1-2√21)=((1+2√21)/10)*(1-2√21)=(1-84)/10=8,3