1-2-3+4+5-6-7+8+...+197-198-199+200

=(1-2-3+4)+(5-6-7+8)+...+(197-198-199+200)

=0+0+...+0

=0

gshegs

     234*(76+24+245)        234*345

=  __________________=    __________=

                4950                      4950

     117*69*10.      39*3*3*23.      39*23

=  ____________=  ____________=   ______

     99*5*10.             3*11*3*5.        11*5

    897

= _____.

      55

15678+36736=

= 215 x 85 + 215 x 1 + 215 x 14

= 215 x ( 85 + 14 +1 ) 

= 215 x 100

= 21500

Đáp án:

215 x 85 + 215 + 215 x 14

=215 x (85 + 14 +1)

=215 x 100

=21500

 215 x 85 +215 +215 x14

=215 x 85 +215 x 1 +215 x14

=215 x (85 + 1+14)

=215 x     100

=   21500

989 < 999     85 197 > 85 192

2002 > 999     85 192 > 85 187

4289 = 4200 + 89     85 197 > 85 187

\(A=\frac{38}{25}+\frac{9}{10}-\frac{11}{15}+...+\frac{197}{4851}-\frac{199}{4950}\)

\(\frac{1}{2}.A=\frac{19}{25}+\frac{9}{20}-\frac{11}{30}+...+\frac{197}{97.99}-\frac{199}{99.100}\)

\(\frac{1}{2}.A=\frac{19}{25}+\frac{9}{4.5}-\frac{11}{5.6}+...+\frac{197}{98.99}-\frac{199}{99.100}\)

\(\frac{1}{2}.A=\frac{19}{25}+\frac{1}{4}+\frac{1}{5}-\left(\frac{1}{5}+\frac{1}{6}\right)+...+\left(\frac{1}{89}+\frac{1}{99}\right)-\left(\frac{1}{99}+\frac{1}{100}\right)\)

\(\frac{1}{2}.A=\frac{19}{25}+\frac{1}{4}-\frac{1}{100}\)

\(\frac{1}{2}.A=\frac{76}{100}+\frac{25}{100}-\frac{1}{100}\)

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

\(A=1:\frac{1}{2}\)

\(A=2\)

85 : 14 = 6,0714 ...

15,30 : 27,8 = 0,5503 ...

197 : 452,3 = 0,4355 ...

24 : 1,8 = 13,3333 ...

\(85\div14=6,0714...\)

\(15,30\div27,8=0,5503...\)

\(197\div452,3=0,4355...\)

\(24\div1,8=13,3333...\)

769 x 85 – 769 x 75

= 769 x (85 – 75)

= 769 x 10 = 7690

\(=2^4\cdot\left(197-97\right)+1=1600+1=1601\)