[latex]frac4{sqrt3+sqrt5}*frac{sqrt3-sqrt5}{sqrt3-sqrt5}= frac{4(sqrt3-sqrt5)}{3-5}= frac{4(sqrt3-sqrt5)}{-2}= -2(sqrt3-sqrt5) = 2sqrt5-2sqrt3\\frac{sqrt6}{sqrt2-2sqrt3}*frac{sqrt2+2sqrt3}{sqrt2+2sqrt3} = frac{sqrt{12}+2sqrt{18}}{2-4*3} =frac{2sqrt3+6sqrt2}{-10} = -frac{sqrt3+3sqrt2}{5}[/latex]
a) 4 4( √3-√5) 4(√3-√5) 4(√3 -√5) --------- *------------------- =-------------- =------------------- = -2(√3-√5) =-2√3+2√5=2√5-2√3 √3+√5 √3-√5 3-5 -2 √6 √2+2√3 √12+2√18 2√3 +6√2 √3+3√2 -------- * ---------------- = --------------------- = ------- --------- = - -------------------- √2-2√3 √2+2√3 2-12 -10 5