有幾題數學難題,想請大家指教!!
有20分.
答我呀!!
1.
2009 2008 2007 3 2
Calculate ------ x ------ x ------ x…x--- x--- .
2008 2007 2006 2 1
Briefly explain how you get the answer.
2.Find the units digit of the expression 1x2x3x ... x2009x2010.
Briefly explain your answer.
3. (+5f)-(+7g)-5f
Hint : Not all the terms in this expression are like terms.
4. The distance between city A and city B is 100 km.A car travels from city A to city B at a constant speed of x km/h and returns at a constant speed of y km/h.Express the time taken for the whole journey in x and y.
請用英文作解答及解釋.
數學難題指教
2010-08-30 8:00 pm
回答 (2)
2010-08-30 8:51 pm
✔ 最佳答案
1.2009 2008 2007 3 2
Calculate ------ x ------ x ------ x…x--- x--- .
2008 2007 2006 2 1
Briefly explain how you get the answer.
圖片參考：http://imgcld.yimg.com/8/n/HA01076848/o/701008300061013873382830.jpg
2.Find the units digit of the expression 1x2x3x ... x2009x2010.
Briefly explain your answer.
10 x 3 = 30
10 x 3454 = 34540
So , 10 x any numbers , the units digit is 0
3. (+5f)-(+7g)-5f
Hint : Not all the terms in this expression are like terms.
= ( -7g )
4. The distance between city A and city B is 100 km.A car travels from city A to city B at a constant speed of x km/h and returns at a constant speed of y km/h.Express the time taken for the whole journey in x and y.
( x + y ) ( hour )
參考: Hope I Can Help You ^_^
2010-09-01 9:38 pm
1.
2009 2008 2007 3 2
Calculate ------ x ------ x ------ x…x--- x--- .
2008 2007 2006 2 1
Briefly explain how you get the answer.2009/2008 x 2008/2007 x 2007/2006 x …. 3/2 x 2/1 =2009/1=2009
2.Find the units digit of the expression 1x2x3x ... x2009x2010.
Briefly explain your answer.
Given a number in decimal form expressed as anan-1an-2 .........a0.b1b2b3......bm, where a1 to an and b1 to bm are n and m digits in its decimal form, before and after the decimal point respectively. Using the algebraic notations we can write this number as:an10n+an-110n-1+an-210n-2+....+a1101+a0100+b110-1+b210-2+b310-3+....+bm10-mThe coefficient of 10 power zero , i.e. a0 is the units digit in this algebraic representation and the number of digits before and after decimal are n and m respectively provided an 0 and bm 0.Any numbers × 10N = the units digit is 0.
, Thus the units digit is 0.
3. (+ 5f )-(+ 7g ) -5f
Hint : Not all the terms in this expression are like terms.
= -7g
4. The distance between city A and city B is 100 km .A car travels from city A to city B at a constant speed of x km/h and returns at a constant speed of y km/h.Express the time taken for the whole journey in x and y.
( 100/x +100/ y ) ( hour ) 頭三條我同樓上個答案都差唔多，但係第四條樓上個答案就一定錯！ X+Y只係時速，唔能夠直接套用。假如X同Y時速分別係200同100公里，唔通時間就係200+100=300小時？
2010-09-02 17:43:52 補充：
都唔明d人點解明知答案一係錯都仲投票=.=
2009 2008 2007 3 2
Calculate ------ x ------ x ------ x…x--- x--- .
2008 2007 2006 2 1
Briefly explain how you get the answer.2009/2008 x 2008/2007 x 2007/2006 x …. 3/2 x 2/1 =2009/1=2009
2.Find the units digit of the expression 1x2x3x ... x2009x2010.
Briefly explain your answer.
Given a number in decimal form expressed as anan-1an-2 .........a0.b1b2b3......bm, where a1 to an and b1 to bm are n and m digits in its decimal form, before and after the decimal point respectively. Using the algebraic notations we can write this number as:an10n+an-110n-1+an-210n-2+....+a1101+a0100+b110-1+b210-2+b310-3+....+bm10-mThe coefficient of 10 power zero , i.e. a0 is the units digit in this algebraic representation and the number of digits before and after decimal are n and m respectively provided an 0 and bm 0.Any numbers × 10N = the units digit is 0.
, Thus the units digit is 0.
3. (+ 5f )-(+ 7g ) -5f
Hint : Not all the terms in this expression are like terms.
= -7g
4. The distance between city A and city B is 100 km .A car travels from city A to city B at a constant speed of x km/h and returns at a constant speed of y km/h.Express the time taken for the whole journey in x and y.
( 100/x +100/ y ) ( hour ) 頭三條我同樓上個答案都差唔多，但係第四條樓上個答案就一定錯！ X+Y只係時速，唔能夠直接套用。假如X同Y時速分別係200同100公里，唔通時間就係200+100=300小時？
2010-09-02 17:43:52 補充：
都唔明d人點解明知答案一係錯都仲投票=.=
收錄日期: 2021-04-16 11:35:45
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