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23 tháng 12 2016

Bài 1:

\(P=\frac{\frac{1}{2003}+\frac{1}{2004}-\frac{1}{2005}}{\frac{5}{2003}+\frac{5}{2004}-\frac{5}{2005}}-\frac{\frac{2}{2002}+\frac{2}{2003}-\frac{2}{2004}}{\frac{3}{2002}+\frac{3}{2003}-\frac{3}{2004}}\)

\(\Rightarrow P=\frac{1\left(\frac{1}{2003}+\frac{1}{2004}-\frac{1}{2005}\right)}{5\left(\frac{1}{2003}+\frac{1}{2004}-\frac{1}{2005}\right)}-\frac{2\left(\frac{1}{2002}+\frac{1}{2003}-\frac{1}{2002}\right)}{3\left(\frac{1}{2002}+\frac{1}{2003}-\frac{1}{2004}\right)}\)

\(\Rightarrow P=\frac{1}{5}-\frac{2}{3}\)

\(\Rightarrow P=\frac{-7}{15}\)

Vậy \(P=\frac{-7}{15}\)

Bài 2:
Ta có: \(S=23+43+63+...+203\)

\(\Rightarrow S=13+10+20+23+...+103+100\)

\(\Rightarrow S=\left(13+23+...+103\right)+\left(10+20+...+100\right)\)

\(\Rightarrow S=3025+450\)

\(\Rightarrow S=3475\)

Vậy S = 3475

23 tháng 12 2016

1. \(P=\frac{\frac{1}{2003}+\frac{1}{2004}-\frac{1}{2005}}{\frac{5}{2003}+\frac{5}{2004}-\frac{5}{2005}}-\frac{\frac{2}{2002}+\frac{2}{2003}-\frac{2}{2004}}{\frac{3}{2002}+\frac{3}{2003}-\frac{3}{2004}}\)

=> P =\(\frac{\frac{1}{2003}+\frac{1}{2004}-\frac{1}{2005}}{5\left(\frac{1}{2003}+\frac{1}{2004}-\frac{1}{2005}\right)}-\frac{2\left(\frac{1}{2002}+\frac{1}{2003}-\frac{1}{2004}\right)}{3\left(\frac{1}{2002}+\frac{1}{2003}-\frac{1}{2004}\right)}\)

=> P = \(\frac{1}{5}-\frac{2}{3}\)

P = \(\frac{3}{15}-\frac{10}{15}\)

=> P =\(\frac{-7}{15}\)

2. ta có:

S = 23 + 43 + 63 +...+ 203

=> S = 13 + 10 + 23 + 20 +...+ 103 + 100

=> S = ( 13 + 23+...+ 103 ) + ( 10 + 20 +...+ 100 )

=> S = 3025 + 550

=> S = 3575

Vậy S = 3575

25 tháng 10 2015

\(ad=bc=>\frac{a}{c}=\frac{b}{d}=>\frac{a^{2004}}{c^{2004}}=\frac{b^{2004}}{d^{2004}}\)

Áp dụng tính chất của dãy tỉ số bằng nhau ta có:

\(\frac{a^{2004}}{c^{2004}}=\frac{b^{2004}}{d^{2004}}=\frac{a^{2003}-b^{2004}}{c^{2004}-d^{2004}}=\frac{a^{2004}+b^{2004}}{c^{2004}+d^{2004}}\)

=>\(\frac{a^{2003}-b^{2004}}{c^{2004}-d^{2004}}=\frac{a^{2004}+b^{2004}}{c^{2004}+d^{2004}}\)

=>\(\frac{a^{2003}-b^{2004}}{a^{2004}+b^{2004}}=\frac{c^{2004}-d^{2004}}{c^{2004}+d^{2004}}\)

25 tháng 10 2015

\(ad=bc\)

\(\Rightarrow\frac{a}{c}=\frac{b}{d}\)

\(\Rightarrow\frac{a^{2004}}{c^{2004}}=\frac{b^{2004}}{d^{2004}}\)

\(\Rightarrow\frac{a^{2004}}{c^{2004}}=\frac{b^{2004}}{d^{2004}}=\frac{a^{2004}-b^{2004}}{c^{2004}-d^{2004}}=\frac{a^{2004}+b^{2004}}{c^{2004}+d^{2004}}\)

\(\Rightarrow\frac{a^{2004}-b^{2004}}{a^{2004}+b^{2004}}=\frac{c^{2004}-d^{2004}}{c^{2004}+d^{2004}}\left(đpcm\right)\)

15 tháng 10 2017

3 tháng 12 2023

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