There are mistakes in highlight parts. Make necessary corrections.
Q1.
x-3≦2x+4
x-2x≦4+3
-x≦7
x≦-7
Q2.
2/x＞5
x/2＞1/5
x＞2/5
Inequalities(2)
2007-07-04 5:58 am
回答 (2)
2007-07-04 6:15 am
其實都好明顯
Q1, 當乘負數去 inequalities時,大細符號要調轉的 . 而Q1 gei只係兩邊乘負1
如果難明gei我舉個例子
-2≦1 , 但當兩邊乘負1時就會出 ,
2≧-1
Q2 , 其實同乘負數去 inequalities差唔多 , 1 over 兩邊都係要將大細符號要調轉的 .
同樣舉個簡單例子
1 / 10 > 1 /20 , 但當兩邊俾1除(即是1 over 兩邊時)就會出 ,
10 < 20
Q1, 當乘負數去 inequalities時,大細符號要調轉的 . 而Q1 gei只係兩邊乘負1
如果難明gei我舉個例子
-2≦1 , 但當兩邊乘負1時就會出 ,
2≧-1
Q2 , 其實同乘負數去 inequalities差唔多 , 1 over 兩邊都係要將大細符號要調轉的 .
同樣舉個簡單例子
1 / 10 > 1 /20 , 但當兩邊俾1除(即是1 over 兩邊時)就會出 ,
10 < 20
2007-07-04 6:07 am
There are mistakes in highlight parts. Make necessary corrections.
Q1.
x-3≦2x+4
x-2x≦4+3
-x≦7
x≦-7<----(correct to x => -7)
Q2.
2/x＞5
(2 - 5x)/x > 0
for x > 0,
2 - 5x > 0
5x < 2
x < 2/5
hence,0 < x < 2/5
for x < 0,
2 - 5x < 0
5x > 2
x > 2/5
no solution
hence,
0 < x < 2/5
Q1.
x-3≦2x+4
x-2x≦4+3
-x≦7
x≦-7<----(correct to x => -7)
Q2.
2/x＞5
(2 - 5x)/x > 0
for x > 0,
2 - 5x > 0
5x < 2
x < 2/5
hence,0 < x < 2/5
for x < 0,
2 - 5x < 0
5x > 2
x > 2/5
no solution
hence,
0 < x < 2/5
收錄日期: 2021-04-12 21:46:23
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070703000051KK04622