(3+3/5)² - (3/5)² - 6 · 6/10 =
[ (15+3)/5 ]² - (3/5)² - 18/5 =
(18/5)² - (3/5)² - 18/5 =
(18/5) [ 18/5 - 1] - (3/5)² =
18 18 - 5 18 · 13 9 234 - 9 225 5· 5· 9
---- · --------- - (3/5)² = --------- - ----- = ---------- = ------ = --------- = 9
5 5 5· 5 5· 5 5· 5 5· 5 5· 5