4 |
7 |
1 |
3 |
當(dāng)x≤
1 |
3 |
-4x+|4-7x|-|1-3x|+4=-4x+4-7x-1+3x+4=7-8x,
式子隨x的變化而變化,不為恒值;
當(dāng)
1 |
3 |
4 |
7 |
-4x+|4-7x|-|1-3x|+4=-4x+4-7x+1-3x+4=9-14x,
式子隨x的變化而變化不為恒值;
當(dāng)x≥
4 |
7 |
-4x+|4-7x|-|1-3x|+4=-4x-4+7x+1-3x+4=1,
式子為恒值1;
故答案兩空分別填:x≥
4 |
7 |
4 |
7 |
1 |
3 |
1 |
3 |
1 |
3 |
4 |
7 |
4 |
7 |
4 |
7 |