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#1 Re: Help Me ! » Need help » 2007-03-15 21:12:53

S=1+(3²-2²)+(5²-4²)+...+(2003²-2002²)
S=1+5+9+13+17+...+4005
S=1+(1+4)+(1+4+4)+...+(1+4*2002/2)
S=1+(5+4005)*1001/2  (from 5 to 4005 we have 1001 items, 5+4005=9+4001=4010
S=1+2007005                                             , we have 1001/2 4010s.)
S=2007006

#2 Re: Help Me ! » The area...... » 2007-03-15 20:21:35

the area of the rectagular is 4608.

#3 Re: Puzzles and Games » Triangles - Squares » 2007-03-15 19:15:39

It must be 0, from my intuition.

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#4 Re: Help Me ! » Help with Math » 2007-03-05 18:44:32

it's easy, try to read your text book carefully! you can solve this problems smoothly next time.

3x+5=8
> 3x=8-5=3
> x=3/3
> x=1

#5 Re: Help Me ! » Need help on percentage. » 2007-03-05 18:40:03

I'm not very sure about your problem.
but, I tried, maybe this is what your want.

100*(100-20)%=80

you have 4 students above 80.

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