Question

Am nevoie de ajutor
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Answer 1

Explicație pas cu pas:

3.a)

$(2x + 1) \in \mathcal{D}_{7} \iff (2x + 1) \in \Big\{- 7; - 1; 1; 7 \Big\} \\ 2x \in \Big\{- 8; - 2; 0; 6 \Big\} \iff 2x \in \Big\{- 4; - 1; 0; 3 \Big\}$

cel mai mic număr natural este: x = 0

b)

$x \in [-3; 7] \iff -3 \leqslant x \leqslant 7$

$-3 \leqslant x \iff x + 3 \geqslant 0 \\ \implies |x + 3| = x + 3$

$x \leqslant 7 \iff x - 7 \leqslant 0 \\ \implies |x - 7| = 7 - x$

$a = |x + 3| + |x - 7| = x + 3 + 7 - x = \bf 10$

c)

(-5; 3] U [-3; 5) = (-5; 5)