2014.18+1995+2011.2013/2013.17+671.3-671.663=-10

cách giải :2014.18+1995+2011.2013 SHIFT STO A

2013.17+671.3-671.663 SHIFT STO B

ALPHA A / ALPHA B=-10

4009.81602209

(\(\frac{121}{122}\). \(\frac{123}{125}\)) .(\(\frac{1995}{1996}\).\(\frac{17}{16}\)- \(\frac{21}{25}\):\(\frac{16}{17}\)).(\(\frac{42}{30}\).\(\frac{75}{23}\)-\(\frac{19}{23}\).\(\frac{210}{38}\))

= (121/122 . 123/125) . ( 1995/1996 . 17/16 - 21/25 : 16/ 17) . 0

= 0

A = 1995 x 873 + 1996 x 127 

A = 1995 x 873 + (1995 + 1) x 127

A = 1995 x 873  + 1995 x 127  + 127

A = 1995 x ( 873 + 127 )  + 127

A = 1995 x 1000 + 127

A = 1995000 + 127

A = 1995127

\(A=\frac{1}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+...+\frac{2}{2011.2013}\right)\)

\(A=\frac{1}{2}.\left(1-\frac{1}{2013}\right)\)

\(A=\frac{1}{2}.\frac{2012}{2013}\)

\(A=\frac{1006}{2013}\)

\(A=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2011.2013}\)

\(A=\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2011}-\frac{1}{2013}\right)\)

\(A=\frac{1}{2}.\left(1-\frac{1}{2013}\right)\)

\(A=\frac{1}{2}.\frac{2012}{2013}\)

\(A=\frac{1006}{2013}\)

A = 1/1. x 1/3 + 1/3 x 1/5 + 1/5 x 1/7 x.....+1/2011 x 1/2013

A=1/1 x 1/2013(bạn triệt tiêu 1/3 ,1/5 ,1/7,1/2011 nha )

A =1/2013 

tất cả đều đặt nhân tử chung bạn ạ

a, 399 x45 + 55x 399 = 399 x (45+55) = 399x 100

1995 x 1996 - 1991x1995= 1995x (1996-1991)=1995 x 5 = 2000 -5= (400 x5) - 1 x 5= 5x (400-1) = 5*399

nên đáp án là bằng 100/5 = 20

hai câu sau làm tương tự , ahihi

theo mình Nguyễn Như Quỳnh làm sai rồi

399 x 45 + 55 x 399 / 1995 x 1996 - 1991 x 1995 = 399 x (45+55) / 1995 x (1996-1991)=399 x 100 / 1995 x 5=399 x 100/ 399x5x5=399x100/399x25=100/25=4

các bạn thấy mình đúng thì k cho mình nha !

ahihi đồ ngu

\(2A=\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}+.....+\frac{2}{2011.2013}\)

\(2A=\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+......+\frac{1}{2011}-\frac{1}{2013}\)

\(2A=\frac{2008}{10065}\)

\(A=\frac{1004}{10065}\)