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( a√2 + b ) • ( √2 + 2 ) = — 2 → 2a + 2a√2 + b√2 + 2b = — 2 → 2a√2 + b√2 = — 2 — 2a — 2b → √2 ( 2a + b ) = — 2 — 2a — 2b = >
= > 2a + b ≠ 0 = > — 2 — 2a — 2b / 2a + b € Q = > negativ ...
= > — 2 — 2a — 2b = 0 < = >
< = > 2a + b = 0 → a = 1 , b = — 2
→ b = — 2
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