Упр.11 Вариант 2 Дидактические материалы ГДЗ Мерзляк Полонский 7 класс (Алгебра)

$$4(x-3)=x+6$$

$$4x-12=x+6$$

$$4x-x=6+12$$

$$3x=18$$

$$x=6$$

$$4-6(x+2)=3-5x$$

$$4-6x-12=3-5x$$

$$-6x+5x=3+12-4$$

$$-x=11$$

$$x=-11$$

$$\left(5x+8\right)-\left(8x+14\right)=9$$

$$5x+8-8x-14=9$$

$$-3x-6=9$$

$$-3x=15$$

$$x=-5$$

$$2{,}7+3y=9(y-2{,}1)$$

$$2{,}7+3y=9y-18{,}9$$

$$3y-9y=-18{,}9-2{,}7$$

$$-6y=-21{,}6$$

$$y=3{,}6$$

$$0{,}3(8-3y)=3{,}2-0{,}8(y-7)$$

$$2{,}4-0{,}9y=3{,}2-0{,}8y+5{,}6$$

$$-0{,}9y+0{,}8y=8{,}8-2{,}4$$

$$-0{,}1y=6{,}4$$

$$y=-64$$

$$\frac{5}{6}\left(\frac{1}{3}x-\frac{1}{5}\right)=3x+3\frac{1}{3}$$

$$\frac{5}{18}x-\frac{1}{6}=3x+3\frac{1}{3}$$

$$\frac{5}{18}x-3x=3\frac{1}{3}+\frac{1}{6}$$

$$-\frac{49}{18}x=\frac{7}{2}$$

$$x=\frac{7}{2}:\left(-\frac{49}{18}\right)=-\frac{9}{7}=-1\frac{2}{7}$$