Question

задание указано на картинке

Answer 1

$frac{( sqrt{17}+ sqrt{23}) ^{2}}{20+ sqrt{391} }= frac{( sqrt{17}) ^{2} +2cdot sqrt{17}cdot sqrt{23}+( sqrt{23}) ^{2}}{20+ sqrt{391} }= frac{17 +2cdot sqrt{391}+23}{20+ sqrt{391} }= \ = frac{40 +2cdot sqrt{391}}{20+ sqrt{391} }=frac{2cdot(20 + sqrt{391})}{20+ sqrt{391} }=2$