Question

6 класс пж 50 бал матем быстро и правильно пж

Answer 1

Ответ:

Подробный ответ на фото

Answer 2

Ответ:

Пошаговое объяснение:

[960]

[1]

$7\leq 2x+3\leq 11\\7-3\leq 2x+3-3\leq11-3\\4\leq2x\leq8\\\frac{4}{2}\leq \frac{2x}{2}\leq\frac{8}{2}\\2\leq x\leq4$

[2]

$-3< 1+2x\leq\ 7\\-4<2x\leq 6\\-2<x\leq 3$

[3]

$-2<\frac{8+x}{7}<4\\-2*7<\frac{8+x}{7}*7<4*7\\-14<8+x<28\\-22<x<20$

[4]

$-7\leq\frac{2x+1}{2}<2\\-7*2\leq 2x+1 <2*2\\-14\leq2x+1<4\\-15\leq 2x <3\\-\frac{15}{2}\leq x <\frac{3}{2}\\-7.5\leq x<1.5$

[961]

[1]

$9-\frac{5x+1}{2} > x+5\\9*2-\frac{5x+1}{2}*2 > x*2+5*2\\18-5x-1>2x+10\\7x<7\\x<1$

[2]

$1.75+\frac{2x}{3}< x+1\frac{2}{3}\\1.75-1\frac{2}{3}<x-\frac{2x}{3}\\\frac{3x}{3}-\frac{2x}{3}>1.75-\frac{5}{3}\\\frac{x}{3}>1.75-\frac{5}{3}\\x>3*(1.75-\frac{5}{3})\\x>5.25-5\\x>0.25$

[3]

$\frac{4+y}{2}-\frac{y+2}{7}< y+3\\\frac{4+y}{2}*14-\frac{y+2}{7}*14< y*14+3*14\\7(4+y)-2(y+2)<14y+42\\28+7y-2y-4<14y+42\\28-4-42<14y-7y+2y\\9y>-18\\y>-2$

[4]

$4+\frac{7y-3}{5} >\frac{3y+5}{4}-\frac{3y}{2}\\4*20+\frac{7y-3}{5}*20 >\frac{3y+5}{4}*20-\frac{3y}{2}*20\\80+4(7y-3)>5(3y+5)-10*3y\\80+28y-12>15y+25-30y\\28y-15y+30y>25-80+12\\43y>-43\\y>-1$