0.6(2x+1) =-1, 8(3x-4)

Вопрос школьника по предмету Математика

1) 0,3x+8=2 0.3x=2-8 0.3x=-6 x=-6/0.3 x = -20

2) 4-x=1+4x -x-4x=1-4 -5x=-3 x=-3/(-5) x = 0.6

3) 7-2(x+3)=9-6x -2x+6x=9-7+6 4x=8 x=8/4 x = 2

4) 4(x-0.5)-2(x+0.3)=-2.6 4x-2x = -2.6+2+0.6 2x = 0 x=0/2 x = 0

5) 0.4x-6= -12 0.4x = -12+6 0.4x = -6 x = -6/0.4 x = -15

6) x+6=5+4x x-4x=5-6 -3x = -1 x = -1/(-3) x = 1/3

7) 13-3(x+1) = 4-5x -3x +5x = 4-13+3 2x = -6 x = -6/2 x = -3

8) 0.2(3x-5)-0.3(x-1) = -0.7 0.6x — 0.3x = -0.7+1-0.3 0.3x = 0 x = 0/0.3 x = 0

1) (7y-2)/(5y-4)>2

(7y-2 -2(5y-4)) / (5y-4) > 0

1) случай {7y-2-10y+8 > 0 {-3y>-6 {y<-6/(-3) {y < 2 0.8 < x < 2

{5y-4 > 0 {5y > 4 {y>4/5 {y > 0.8

2)случай {7y-2-10y + 8<0 {-3y<-6 {y>-6/(-3) {y > 2 Пустое множество

{5y-4 < 0 {5y < 4 {y<4/5 {y < 0.8

Ответ. ( 0,8; 2)

2) 8y+2 -(5y+3) > 5

8y — 5y > 5-2+3

3y > 6

y > 6/3

y > 2

3) 3*(2y+1.5)-(3+2y+1.5) > 8

6y-2y > 8-4.5+4.5

4y > 8

y> 8/4

y > 2

4) 4*(3y-0.5) — 4 -3y-0.5 >3.5

12y — 3y < 3.5 +2+4+0.5

9y < 10

y < 10/9