Ta có: \(\frac{15}{16}\times\frac{24}{25}\times\ldots\times\frac{9999}{10000}\)

\(=\left(1-\frac{1}{16}\right)\times\left(1-\frac{1}{25}\right)\times\ldots\times\left(1-\frac{1}{10000}\right)\)

\(=\left(1-\frac14\right)\times\left(1-\frac15\right)\times\ldots\times\left(1-\frac{1}{100}\right)\times\left(1+\frac14\right)\times\left(1+\frac15\right)\times\ldots\times\left(1+\frac{1}{100}\right)\)

\(=\frac34\times\frac45\times\ldots\times\frac{99}{100}\times\frac54\times\frac65\times\ldots\times\frac{101}{100}\)

\(=\frac{3}{100}\times\frac{101}{4}=\frac{303}{400}\)

Ta có: \(\dfrac{1}{5}+\dfrac{4}{10}+\dfrac{9}{15}+\dfrac{16}{20}+\dfrac{25}{25}+\dfrac{36}{30}+\dfrac{49}{35}+\dfrac{64}{40}+\dfrac{81}{45}\)

\(=\dfrac{1}{5}+\dfrac{2}{5}+\dfrac{3}{5}+\dfrac{4}{5}+\dfrac{5}{5}+\dfrac{6}{5}+\dfrac{7}{5}+\dfrac{8}{5}+\dfrac{9}{5}\)

\(=\dfrac{45}{5}=9\)

\(\dfrac{1}{5}+\dfrac{4}{10}+\dfrac{9}{15}+...+\dfrac{81}{45}\\ =\dfrac{1}{5}+\dfrac{2}{5}+\dfrac{3}{5}+...+\dfrac{9}{15}\\ =\dfrac{\left(1+2+3+...+9\right)}{15}=\dfrac{\left(1+9\right)x9:2}{15}\\ =\dfrac{10x9:2}{15}=\dfrac{45}{15}=3\)

\(0,5\times40\times0,2\times20\times0,25\)

\(=\left(0,5\times0,2\right)\times\left(40\times20\times0,25\right)\)

\(=0,1\times200\)

\(=20\)

~ Hok tốt ~

#)Trả lời :

c) ( 67,895 x 0,5 + 3,1416 x 0,5 ) x ( 9 x 0,9 + 0,9 - 0,9 x 10 )

= ( 67,895 x 0,5 + 3,1416 x 0,5 ) x ( 8,1 + 0,9 - 9 ) 

= ( 67,895 x 0,5 + 3,1416 x 0,5 ) x ( 9 - 9 )

= ( 67,895 x 0,5 + 3,1416 x 0,5 ) x 0

= 0

      #~Will~be~Pens~#

\(3.6\times4.2+0.36\times25+36\times0.33\)

\(=36\times0.42+36\times0.25+36\times0.33\)

\(=36\times\left(0.42+0.25+0.33\right)\)

\(=36\times1=36\)

= (8x15x24x35x...x99) / (9x16x25x36x...x100)

= (4x2x5x3x6x2x2x5x7x...x9x11) / (9x4x2x2x5x5x6x3x2x...x25x4)

= 11/(4x25)

= 11/100

Mình không chắc lắm

\(0,9\times6+0,9\times6\times15+3,6=0,9\times\left(6+5\times15\right)+3,6=0,9\times10\)\(=90+3,6=93,6\)

693.036

 1/5 + 4/10 +9/15 + 16/20 + 25/25 + 36/30 + 49/35 + 64/40 + 81/45

=1/5 + 2/5 + 3/5 +...+ 9/5

=45/5=9

\(\frac{1}{5}+\frac{4}{10}+\frac{9}{15}+\frac{16}{20}+\frac{25}{25}+\frac{36}{30}+\frac{49}{35}+\frac{64}{40}+\frac{81}{45}\)

\(=\frac{1}{5}+\frac{1}{5}+\frac{3}{5}+\frac{4}{5}+\frac{5}{5}+\frac{6}{5}+\frac{7}{5}+\frac{8}{5}+\frac{9}{5}\)

\(=\frac{\left(9+1\right)\cdot9:2}{5}=\frac{45}{5}=9\)

0,9 x 35 + 1,8 x 9 + 9 x 2,7 + 3,6 x 5

= 0,9 x 35 + 1,8 x 9 + 9 x 2,7 + 0,9 x 4 x 5

= 0,9 x 35 + 1,8 x 9 + 9 x 2,7 + 0,9 x 20

= 9 x ( 1,8 + 2,7 ) + 0,9 x ( 35 + 20 )

= 9 x 4,5 + 0,9 x 55

= 40,5 + 49,5

= 90

90 bạn ạ

1) \(25+37-48-25-37=\left(25-25\right)+\left(37-37\right)-48=-48\)

2) \(37+35+36+37-14-15-16-17\)

\(=\left(37-17\right)+\left(35-15\right)+\left(36-16\right)+\left(37-14\right)\)

\(=20+20+20+23=83\)

3600

3600