1) 3,(6)→ -1,5(3) и 1,5(3) .
2) 2 +√20 = 2 +2√5 → -1 - √5 и 1 + √5.
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|6 -2√3| =6 -2√3, т.к . (6 -2√3) =√36 -√2²*3 = √36 -√12 > 0 .
|-5 + √20 | = -(-5 + √20) =5 - √20 т.к . -5 + √20 = -√25 +√20 <0.<br>------------------
-2< a <√8⇔ -2 < a < 2√2 .( - 2 < a < 2,82 || ≈2*1,41 || ) ;<br>-√10 < a < √10⇒ ≈ 3,16 < a < 3,16 .<br>------------------