b) 35 x 24 + 35 x 76 +55 x 19 +55 x 91

= 35 x ( 24 + 76 ) + 55 x ( 19 + 91 )

= 35 x100 +55 x 100

= 100 x ( 55 + 35 )

= 90 x 100 =9 000

c) \(6\cdot25\cdot4+4\cdot19\cdot6-2\cdot14\cdot12\)

\(=24\cdot25+24\cdot19-24\cdot14\)

\(=24\left(25+19-14\right)\)

\(=24\cdot30=720\)

d) \(19\cdot64+76\cdot34\)

\(=76\cdot19+76\cdot34\)

\(=76\left(19+34\right)=76\cdot53=4028\)

a) 2 x 16 x 50 x 25

= ( 2 x 50 ) x ( 16 x 25 )

= 100 x 400 

= 40 000

=(3.8.15.24.36.48.63)/(4.9.16.25.36.49.64)=81/140

A=17x32+64x83+36x83+68x17

   A=17x32+17x68+64x83+36x83

A=17x(32+68)+83x(64+36)

A=17x100+83x100

A=100x(83+17)

A=100x100

A=10000

A=17x32+64x83+36x83+68x17

  = 17x32+68x17+ 64x83+36x83

  = 17 x (32 +68) +83x(64+36)

  =  17x100 + 83x100

  =      1700 + 8300

  =             10000

*k cho mình nha

\(A=\frac{8}{9}.\ \frac{15}{16}.\ \frac{24}{25}.\ \frac{35}{36}.\ \frac{48}{49}.\ \frac{63}{64}\)

\(A=\frac{2.4}{3^2}.\ \frac{3.5}{4^2}.\ \frac{4.6}{5^2}.\ \frac{5.7}{6^2}.\ \frac{6.8}{7^2}.\ \frac{7.9}{8^2}\)

\(A=\frac{2.3.4^2.5^2.6^2.7^2.8.9}{3^2.4^2.5^2.6^2.7^2.8^2}\)

\(A=\frac{2.9}{3.8}\)

\(A=\frac{3}{4}\)

A=\frac{8}{9} 

mình biết đáp án là : \(\frac{9}{16}\)thôi,còn cách giải thì mình không chắc chắn nên không viết ra

 \(\frac{3.2.4.3.5.4.6.5.7.6.8.7.9}{4.3.3.4.4.5.5.6.6.7.7.8.8}\)= \(\frac{9}{16}\)

Ta có: \(A=\frac34\cdot\frac89\cdot\frac{15}{16}\cdot\frac{24}{25}\cdot\frac{35}{36}\cdot\frac{48}{49}\cdot\frac{63}{64}\)

\(=\frac{1\cdot3}{2\cdot2}\cdot\frac{2\cdot4}{3\cdot3}\cdot\frac{3\cdot5}{4\cdot4}\cdot\frac{4\cdot6}{5\cdot5}\cdot\frac{5\cdot7}{6\cdot6}\cdot\frac{6\cdot8}{7\cdot7}\cdot\frac{7\cdot9}{8\cdot8}\)

\(=\frac{1\cdot2\cdot\ldots\cdot7}{2\cdot3\cdot\ldots\cdot8}\cdot\frac{3\cdot4\cdot\ldots\cdot9}{2\cdot3\cdot\ldots\cdot8}=\frac18\cdot\frac92=\frac{9}{16}\)