1. В

[tex]49 - 7x \geqslant 0 \\ - 7x \geqslant - 49 \: \: | \div ( - 7) \\ x \leqslant 7[/tex]

2. Б

[tex]\displaystyle\bf\\\left \{ {{3x - 15 < 0} \atop {6x - 2 \geqslant 10 }} \right. \\ \displaystyle\bf\\\left \{ {{3x < 15 \: \: | \div 3 } \atop {6x \geqslant 12 \: \: | \div 6}} \right. \\ \displaystyle\bf\\\left \{ {{x < 5} \atop {x \geqslant 2 }} \right. \\ \\ x \: \epsilon \: [2; \: 5)[/tex]

3. Б

[tex]q = \frac{b_{n}}{b_{n - 1}} = \frac{b_{8}}{b_{7}} = \frac{ 9}{ - 3} = - 3[/tex]