f.2代數不等式

1) 2(8- m/2) > 2- 3/2 (m-5)
16 - m > 2 - 3/2m + 15/2
16 - m > 2 - 1.5m + 7.5
16 - 2 - 7.5 > m-1.5m
-0.5m > 6.5
m < -13

2007-03-27 21:17:30 補充：
顛倒了正負號...-0.5m 6.5m -13

1) 2(8- m/2) &gt; 2- 3/2 (m-5)
16 - m &gt; 2 - 3/2m + 15/2
1/2m&gt;-14+15/2
1/2m&gt;-13/2
m&gt;-13

2(8-m/2) &gt; 2-3/2(m-5) 跟 2(8-m/2) &gt; 2-3/[2(m-5)] 是不同的, 請留意.
我想, 你想問的是前者.
答案應該是 m &gt;-13. 上面已有朋友答對, 不在此重覆, 其他人都答錯.

2(8-2/m) 2-2/3(m-5)
=16-m =2-2/3m-15
=2/4-3m+15
=2/19-3m
32-2m &gt;9-3m
32-2m-19+3m&gt;0
13+m&gt;0
m&lt;-13

1)2(8- m/2) &gt; 2- 3/2 (m-5)

16-m/2&gt;2-3/2m-7.5

16-2+7.5&gt;-3/2m+m/2

21.5&gt;-m

m&gt;2.5

2(8- m/2) &gt; 2- 3/2 (m-5)

16 - m &gt; 2 - 3/2m + 15/2

16 - 2 - 7.5 &gt; m-1.5m

-0.5m &gt; 6.5

m &lt; -13
=======

2(8- m/2) &gt; 2- 3/2 (m-5)

R.H.S. = 2 - 3m/2 + 15/2
= 9.5 - 1.5m

L.H.S = 16 - m
= 24 - 1.5m

Because 24 -1.5m &gt; 9.5 -1.5m, so 2(8- m/2) &gt; 2- 3/2 (m-5)

2(8- m/2) &gt; 2- 3/2 (m-5)
16-2m&gt;4-6/(M-5)
16-2m+6/(m-5)&gt;4
16-2m+6&gt;4m-20
42&gt;6m
7&gt;m


答案詳盡

16-m&gt;2-3/2m+15/2
16-m&gt;-3/2m+19/2
1/2m&gt;-13/2
m&gt;-13