Решение:
a^2+8a+16=(a+4)^2 Вот и всё!
26 26*(5 -2√3) 26*(5 -2√3)
--------------- = -------------------------------- = ---------------------------- =
(5+2√3) (5+2√3)(5-2√3) 5² -(2√3)²
26*(5 -2√3) 26*(5 -2√3)
= ----------------------- = --------------------- = 2*(5 -2√3) = 10-4√3
25 - 12 13
7√27<span> = 7√9*3 = 7*3</span>√3=21<span>√3</span>