17 x 8 + 51 x 4 = ( 17 x 8 ) + ( 51 x 4 )

                         =  136 + 204 

                         =   340 

chị ko biết nữa vì lớp 5 rồi 

đại đó em , đúng thì tk 

sai thì .................................. thôi em ạ 

chúc em hok tốt # nha

17.8+51.4 

\(\Leftrightarrow\)17.(8 + 3.4)

\(\Leftrightarrow\)17.20 =340

vậy

a) 19,17x25x4=19,17(25x4)=19,17x100=1917

b)1,79x(8x125)=1,79x1000=1790

chúc bạn học tốt

= 3/8 x (5/4 + 3/4)
= 3/8 x 8/4
= 3/8 x 2
= ...........

3/8x[5/4+3/4]

3/8x2

3/4

7/8 x 1/4 + 7/8 x 2/4 + 7/8

=7/8 x\(\left(\dfrac{1}{4}+\dfrac{2}{4}\right)\) + 7/8

=7/8 x 3/4 + 7/8

=7/8 x \(\left(\dfrac{3}{4}+1\right)\)

=7/8 x 7/4

=49/32

`7/8 xx 1/4 + 7/8 xx 2/4 + 7/8`

`= 7/8 xx 1/4 + 7/8 xx 2/4 + 7/8xx1`

`= 7/8 xx (1/4 +2/4+1)`

`= 7/8 xx ( 3/4 + 4/4)`

`= 7/8 xx 7/4`

`= 49/32`

` @ nkhanh`

\(125\times25\times8\times4\)

\(=\left(125\times8\right)\times\left(25\times4\right)\)

\(=1000\times100\)

\(100000\)

125 x 25 x 8 x 4

= (125 x 8) x (25 x 4)

= 1000 x 100

= 100 000

      \(202x\frac{3}{4}+202x\frac{5}{4}+202x8\)

\(=202x\left(\frac{3}{4}+\frac{5}{4}+8\right)\)

\(=202x\left(\frac{8}{4}+8\right)\)

\(=202x\left(2+8\right)\)

\(=202x10\)

\(=2020\)

\(=202*(\frac{3}{4}+ \frac{5}{4}+8) = 202*9 = 1818\)

\(56\times48+51\times56+56\)
\(=56\times48+51\times56+56\times1\)
\(=56\times\left(48+51+1\right)\)
\(=56\times100\)
\(=5600\)
#kễnh

   8,12 x 6 + 16,24 x 4 - 4,06 x 8

= 8,12 x 6 + 8,12 x 2 x 4 - 8,12 x 0,5 x 8

= 8,12 x [6 + 8 - 4]

= 8,12 x 10

= 81,2

   8,12 x 6 + 16,24 x 4 - 4,06 x 8

= 8,12 x 6 + 8,12 x 2 x 4 - 8,12 x 0,5 x 8

= 8,12 x [6 + 8 - 4]

= 8,12 x 10

= 81,2