1) {4x+9>-15
{2-x≤5
4x+9 >-15
4x>-15-9
4x>-24
x>-6
2-x≤5
-x≤5-2
-x≤3
x≥ -3
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------- -6 ------------- -3 --------------
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x≥ -3
Ответ: х≥ -3
2) {2x+3≥x-1
{5x-22≤x+2
2x+3≥x-1
2x-x≥ -1-3
x≥ -4
5x-22≤x+2
5x-x≤2+22
4x≤24
x≤6
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------- -4 --------------- 6-------------
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-4≤x≤6
Ответ: -4≤х≤6
3) {1-0.5x<4-x<br> {9-2.8x>6-1.3x
1-0.5x<4-x<br>-0.5x+x<4-1<br>0.5x<3<br>x<6<br>
9-2.8x>6-1.3x
-2.8x+1.3x>6-9
-1.5x>-3
x<2<br>\\\\\\\\\\\\\\\\\\\\\\\\\
------- 2 -------------- 6 --------------
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x<2<br>Ответ: х<2