625 nhé bạn

TL:

25 x 25 = 625

HT

@@@@@@

47*95+2*47*2+47*1

47*95+47*4+47*1

47*(95+4+1)

47*100

=4700

bằng 419945

25x9x4x100:1000

=(25x4)x9x100:1000

=100x9x100:1000

=10000:1000x9

=10x9

=90

26x15+24x15+50x15

=15x(26+24+50)

=15x100

=1500

26 x 15 + 24 x 15 + 50 x 15

= ( 26 + 24 + 50 ) x 15

= 100 x 15

= 1500

Đặt Tổng trên là A

A     = 1/1.3 + 1/3.5 + 1/5.7 + .... + 1/2005.2007

2. A = 2 . ( 1/1.3 + 1/3.5 + 1/5.7 + .... + 1/2005.2007 )

2A   =  2/1.3  +  2/3.5  +  2/5.7  + ..... + 2/2005.2007

2A   =  1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 + ..... + 1/2005 - 1/2007

2A   =   1  -  1/2007

2A   =    2006/2007

 A     =  2006/2007 : 2

A      =  2006/4014

- Hok Tot - 

               \(\dfrac{1}{1\times3}+\dfrac{1}{3\times5}+\dfrac{1}{5\times7}+....+\dfrac{1}{2005\times2007}\)

=        \(\dfrac{1}{2}\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{2005}-\dfrac{1}{2007}\right)\)

=        \(\dfrac{1}{2}\times\left(\dfrac{1}{1}-\dfrac{1}{2007}\right)\) 

=        \(\dfrac{1}{2}\times\dfrac{2006}{2007}\)

=              \(\dfrac{1003}{2007}\)

\(\frac{2002x2005-1002}{2002x2004+1000}\)

\(=\frac{2002x(2004+1)-1002}{2002x2004+1000}\)

\(=\frac{2002x2004+2002 x 1- 1002}{2002x2004+1000}\)

\(=\frac{2002x2004+2002-1002}{2002x2004+1000}\)

\(=\frac{2002x2004+1000}{2002x2004+1000}\)

\(=1\)

1 + 9 + 2 + 8 + 3 + 7 + 3 + 5 + 6 + 7 =  51

= 10+10+10+10+11

=51

A = 3457 - 27\(\times\) 48 - 48 \(\times\) 73 + 6543

A =(3457 + 6543) - ( 27 \(\times\) 48 + 48 \(\times\) 73)

A = 10 000 - 48 \(\times\) ( 27 + 73)

A = 10 000 - 48 \(\times\) 100

A = 100 \(\times\) ( 100 - 48)

A = 100 \(\times\) 52

A = 5200

A = 3457 - 27$\times$ 48 - 48 $\times$ 73 + 6543

A =(3457 + 6543) - ( 27 $\times$ 48 + 48 $\times$ 73)

A = 10 000 - 48 $\times$ ( 27 + 73)

A = 10 000 - 48 $\times$ 100

A = 100 $\times$ ( 100 - 48)

A = 100 $\times$ 52

A = 5200

HT!

345 - 612 + 1655 - 388

= (345 + 1655) - (612 + 388)

= 2000 - 1000

= 1000

345 - 612 + 1655 - 388

= (345 + 1655) - (612 + 388)

= 2000 - 1000

= 1000

Chúc cậu học tốt☘✿