4 uždavinys
Skaičius $$|3-\sqrt {8}|-|\sqrt {8}-4|$$ lygus:
A $$-2\cdot \sqrt {8}+1$$ B - 1 C $$2\cdot \sqrt {8}-1$$ D 7
Sprendimas:
| 3-saknis(
8) |-| saknis(8)-4 | =
8) |-| saknis(8)-4 | = |
|
| 3-saknis(8) |-| saknis(8)-4 | = $$|3-\sqrt {8}|-|\sqrt {8}-4|$$ =
8) |-| saknis(8)-4 | = $$|3-\sqrt {8}|-|\sqrt {8}-4|$$ = $${\normalsize |3-\sqrt {8}|}$$ = $${\normalsize (3-\sqrt {8})}$$, nes 3 > $${\normalsize \sqrt {8}}$$
(3-saknis(8))-| saknis(8)-4 | = $$(3-\sqrt {8})-|\sqrt {8}-4|$$ =
8))-| saknis(8)-4 | = $$(3-\sqrt {8})-|\sqrt {8}-4|$$ = $${\normalsize -|\sqrt {8}-4|}$$ = $${\normalsize (\sqrt {8}-4)}$$. Pasikeičia ženklas, nes $${\normalsize \sqrt {8}}$$ < 4
(3-saknis(8))+(saknis(8)-4) = $$(3-\sqrt {8})+(\sqrt {8}-4)$$ =
8))+(saknis(8)-4) = $$(3-\sqrt {8})+(\sqrt {8}-4)$$ = 3-saknis(8)+(saknis(8)-4) = $$3-\sqrt {8}+(\sqrt {8}-4)$$ =
8)+(saknis(8)-4) = $$3-\sqrt {8}+(\sqrt {8}-4)$$ = 3-saknis(8)+saknis(8)-4 = $$3-\sqrt {8}+\sqrt {8}-4$$ =
8)+saknis(8)-4 = $$3-\sqrt {8}+\sqrt {8}-4$$ = 3+0-4 = $$3+0-4$$ =
3-4 = $$3-4$$ =
-1$$-1$$
Atsakymas: B