=100x99=9900

25 x 33 x 4 x 3

= (25x 4) x (33x 3)

= 100 x 99

=9900

(25x4)x(33x3)

100x99

=9900

xin hãy giúp mik ik

a, 8600
b, 5000

86x121-86x22+86=
 86x121-86x22+86x1=
  86x(121-22+1)|=
   86x100=8600
25x191-100+25x13=
25x191-25x4+25x13=
25x(191-4+13)=
25x200=5000

\(25:x=7-2\Rightarrow25:x=5\Rightarrow x=5\)

\(265+x=723+45\Rightarrow x=723+45-265\Rightarrow x=503\)

\(x-234=578-323\Rightarrow x=578-323+234\Rightarrow x=489\)

25:x=7-2

25:x=5

x=25:5

x=5

265+x=723+45

265+x=768

x=768-265

x=503

x-234=578-323

x-234=255

x=255+234

x=489

12345 x 17 + 23 x 12345 + 12345 + 12345 x 35 + 12345 x 24

= 12345 x 17 + 23 x 12345 + 12345 x 1 + 12345 x 35 + 12345 x 24

=  12345  x (17 + 23 + 1 + 35 + 24)

= 12345  x 100

= 1234500

5/8x16/7x21/25

=1/1x2/1x3/5

=6/5

11/12:22/30x6/15

=11/12x30/22x6/15

=1/2x1/2x1/2

=1/8

5/8x16/7x21/25

=1/1x2/1x3/5

=6/5

11/12:22/30x6/15

=11/12x30/22x6/15

=1/2x1/2x1/2

=1/8

\(=\dfrac{3}{9}\cdot\dfrac{9}{11}\cdot\dfrac{22}{25}\cdot\dfrac{5}{7}\cdot\dfrac{7}{10}=\dfrac{3}{11}\cdot\dfrac{22}{25}\cdot\dfrac{5}{10}=3\cdot2\cdot\dfrac{1}{2}\cdot\dfrac{1}{5}=\dfrac{3}{5}\)

\(=\dfrac{3x4x9x11x2x5x7}{4x9x11x5x5x10}=\dfrac{3x2x7}{10}=\dfrac{42}{10}=\dfrac{21}{5}\)

=3/9⋅9/11⋅22/25⋅5/7⋅7/10=3/11⋅22/25⋅5/10=3⋅2⋅1/2⋅1/5=3/5