5條數學題

2007-09-08 3:24 am
1. 根號27+根號8+根號75
2. 根號54-根號24-根號8+根號32
3. 2根號12乘4根號3
4. 根號28-根號112-根號175
5. 11根號20+2根號32-3根號245-3根號18
更新1:

第3題打錯 3. 22根號12乘4根號8

回答 (3)

2007-09-09 7:01 pm
1. √27+√8+√75
= √9√3+√4√2+√25√3
= 3√3+2√2+5√3
= 8√3+2√2


2. √54-√24-√8+√32
= √9√6-√4√6-√4√2+√16√2
= 3√6-2√6-2√2+4√2
= √6+2√2


3. 22√12*4√8
= 22√4√3*4√4√2
= (44√3)*(8√2)
= 352√6


4. √28-√112-√175
= √4√7-√16√7-√25√7
= 2√7-4√7-5√7
= -7√7


5. 11√20+2√32-3√245-3√18
= 11√4√5+2√16√2-3√49√5-3√9√2
= 22√5+8√2-21√5-9√2
= √5-√2
2007-09-08 10:43 pm
1. 根號27+根號8+根號75
=3根號3+2根號2+5根號3
=8根號3+2根號2
2. 根號54-根號24-根號8+根號32
=3根號6-2根號6-2根號2+4根號2
=根號6-6根號2
3. 22根號12X4根號8
=44根號3X8根號2
4. 根號28-根號112-根號175
=2根號7-4根號7-5根號7
=-7根號7
5. 11根號20+2根號32-3根號245-3根號18
=22根號5+8根號2-21根號5-9根號2
=根號5-根號2
參考: me
2007-09-08 3:34 am
1. 根號27+根號8+根號75
=3根號3+2根號2+5根號3
=8根號3+2根號2

2. 根號54-根號24-根號8+根號32
=3根號6-4根號6-2根號2+4根號2
= -根號6+2根號2

3. 2根號12乘4根號3
=8根號36
=48

4. 根號28-根號112-根號175
=2根號7-4根號7-5根號7
= -7根號7

5. 11根號20+2根號32-3根號245-3根號18
=22根號5+8根號2-21根號5-9根號2
=根號5-根號2


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