Question

Va rog ajutati ma ex 7 si 8

Answer 1

$7)a) {x}^{2} = 1$

$x = \pm \sqrt{1}$

$x = \pm1$

$b) {x}^{2} = 100$

$x = \pm \sqrt{100}$

$x = \pm10$

$8)A=\left \{ x\:\in\:\mathbb{Z}\:| \:|x|\leq 3\right \} \\ \: \: \: \: B=\left \{ x\:\in\:\mathbb{{N}^{*}}\:| \:2x\leq -x+10 \right \}$

$|x| = | - x| = x$

$|0| = 0 \leq3$

$| - 1| = |1| = 1 \leq3$

$| - 2| = |2| = 2 \leq3$

$| - 3| = |3| = 3 \leq3$

$= > x \: \in \: \left \{ 0,\pm1,\pm2,\pm3 \right \}$

$= > A=\left \{ 0,\pm1,\pm2,\pm3 \right \}$

$2x \leq - x + 10$

$2x + x \leq10$

$3x \leq10$

$x \leq \frac{10}{3}$

$x \leq3.(3)$

$x \: \in \: \mathbb{{N}^{*}} = > x \: \in \: \left \{ 1,2,3 \right \}$

$= > B=\left \{ 1,2,3 \right \}$