Question

Помогите решить систему неравенств...
$left { {{7+2x>5+x} atop {3x+2<8+x}} right.$
$left { {{7+2x>5+x} atop {3x+2<8+x}} right.$
$left { {{1-0.5x<4-x} atop {9-2.8x>6-1.3x}} right.$
$left { {{0.4x-1<0.5x-1.7} atop {2.7x-10<0.9x-1}} right.$
$left { {{2.8x-17 geq 0.3x-4.5} atop {12.3x-16.6 leq 7.1x+19.8}} right.$

Answer 1

1) 7 + 2x > 5 + x;  2x - x > 5 - 7;  x > -2

3x + 2 < 8 + x;  3x - x < 8 - 2;  2x < 6; x < 3

(-2 < x < 3)

2)  1 - 0.5x < 4 - x;  x - 0.5x < 4 - 1;  0.5x < 3;  x < 6

9 - 2.8x > 6 - 1.3x;  2.8x - 1.3x < 9 - 6; 1.5x < 3; x < 2

(x < 2)

3) 0.4x - 1 < 0.5x - 1.7;  0.5x - 0.4x > 1.7 - 1;  0.1x > 0.7;  x > 7

2.7x - 10 < 0.9x - 1;  2.7x - 0.9 < 10 - 1; 1.8x < 9;  x < 5

(x < 5; x > 7)

4) 2.8x - 17 >= 0.3x - 4.5;  2.8x - 0.3x >= 17 - 4.5;  2.5x >= 12.5;  x >= 5;

12.3x - 16.6 <= 7.1x + 19.8;  12.3x - 7.1x <= 19.8 + 16.6; 5.2x <= 36.4; x <= 7;

[5 <= x <= 7]