Đề bài có lẽ sai thừa số thứ hai phải là 125125x127-127127x125

Khi đó thừa số thứ hai sẽ là

125x1001x127-127x1001x125=0

Tích trên sẽ bằng 0
 

=0 vì thừa số sau bằng 0 nên tích bằng 0

=(1+...2005)x(125x1001x127-127x1001x125)

=(1+...2005)x0(cả hai vế giống nhau nên trừ đi thì =0)

=0

( 1 + 3 + 5 + 7 +... + 2003 + 2005 ) x ( 125125 x 127 - 127127 x 125 )

= ( 1 + 3 + 5 + 7 + ... + 2003 + 2005 ) x ( 125 x 1001 x 127 - 127 x 1001 x 125 )

= ( 1 + 3 + 5 + 7 + ... + 2003 + 2005 ) x 0

= 0

~ Thiên Mã ~

lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooolllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll

\(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot...\cdot\dfrac{7}{8}=\dfrac{1}{8}\)

`= 1/2 xx 2/3 xx...xx 7/8`

`= 1/8`

\(=\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{6}{7}\times\dfrac{7}{8}\\ =\dfrac{1}{8}\)

Ta có:

  (1+3+5+...+2005)x(125125x127-127127x125)

=(1+3+5+...+2005)x(125x1001x127-127x1001x125)

=(1+3+5+...+2005)x0

=0

a+b=10

a+c=25

b+c=18

a+b=10

a+c=25

b+c=18

a+b=10

a+c=25

b+c=18

a+b=10

a+c=25

b+c=18

a+b=10

a+c=25

b+c=18

a+b=10

a+c=25

b+c=18

a+b=10

a+c=25

b+c=18

thank you VRCT _gnk_Thùy Linh

( 1 + 3 + 5 +.....+ 2005) * ( 125125 * 127 - 127127 * 125 )

= ( 1+3+5+....+2005) * ( 125 * 1001 * 127 - 127 * 1001 * 125)

= (1 +3+5+....+2005) * 0

= 0

k cho mình nha bạn...!

Ta có:(1+3+5+...+2005)x(125125x127-127127x125)

       =(1+3+5+...+2005)x(125x1001x127-127x1001x125)

       =(1+3+5+...+2005)x0

       =0

   ( 1 + 3 + 5 + ...+ 2005 )  . ( 125125 . 127 - 127127 . 125 )

= ( 1 + 3 + 5 + ... + 2005 ) .  ( 125 . 1001 x 127 - 127 x 1001 x 125 )

= ( 1 + 3 + 5 + .. + 2005 ) .          0

=   0

Ta có: \(\dfrac{-5}{13}\cdot\dfrac{3}{7}-\dfrac{2}{17}\cdot\dfrac{8}{13}+\dfrac{5}{13}\cdot\dfrac{1}{7}\)

\(=\dfrac{5}{13}\left(-\dfrac{3}{7}+\dfrac{1}{7}\right)-\dfrac{2}{17}\cdot\dfrac{8}{13}\)

\(=\dfrac{5}{13}\cdot\dfrac{-2}{7}-\dfrac{2}{17}\cdot\dfrac{8}{13}\)

\(=\dfrac{-10}{91}-\dfrac{16}{221}\)

\(=\dfrac{-282}{1547}\)

\(\dfrac{-5}{13}.\dfrac{3}{7}-\dfrac{2}{17}.\dfrac{8}{13}+\dfrac{5}{13}.\dfrac{1}{7}\) 

\(=\dfrac{5}{13}.\dfrac{-3}{7}-\dfrac{2}{17}.\dfrac{8}{13}+\dfrac{5}{13}.\dfrac{1}{7}\)

\(=\dfrac{5}{13}.\left(\dfrac{-3}{7}+\dfrac{1}{7}\right)+\dfrac{-2}{17}.\dfrac{8}{13}\) 

\(=\dfrac{5}{13}.\dfrac{-2}{7}+\dfrac{-2}{13}.\dfrac{8}{17}\)

\(=\dfrac{-2}{13}.\dfrac{5}{7}+\dfrac{-2}{13}.\dfrac{8}{17}\) 

\(=\dfrac{-2}{13}.\left(\dfrac{5}{7}+\dfrac{8}{17}\right)\) 

\(=\dfrac{-2}{13}.\dfrac{141}{119}\) 

\(=\dfrac{-282}{1547}\)