32 + 19 - x = 28 

51 - x = 28 

x = 51 - 28 = 23

Lời giải:

$4\times 8+19-x=28$

$32+19-x=28$

$51-x=28$

$x=51-28=23$

4x8+19-x=28

4x8+(19-x)=28

32+(19-x)=28

19-x=28-36

19-x=(-8)

x=19-(-8)

x=19+8

x=27

= 17

**** cho mk nha

3:4x8:2-2+8x2=17

= 3/4 x 8/9 x 15/16 x ... x 9999/10000

= 3 x 8 x 15 x ... x 9999/ 4 x 9 x 16 x ... x 10000

= (1 x 3) x (2 x 4) x (3 x 5) x ... x (99 x 101)/ (2 x 2) x (3 x 3) x (4 x 4) x ... x (100 x 100)

= (1 x 2 x 3 x ... x 99) x (3 x 4 x 5 x ... x 101)/ (2 x 3 x 4 x ... x 100) x (2 x 3 x 4 x ... x 100)

= 1x 101/ 100 x 2

= 101/200

= 3/4 x 8/9 x 15/16 x ... x 9999/10000

= 3 x 8 x 15 x ... x 9999/ 4 x 9 x 16 x ... x 10000

= (1 x 3) x (2 x 4) x (3 x 5) x ... x (99 x 101)/ (2 x 2) x (3 x 3) x (4 x 4) x ... x (100 x 100)

= (1 x 2 x 3 x ... x 99) x (3 x 4 x 5 x ... x 101)/ (2 x 3 x 4 x ... x 100) x (2 x 3 x 4 x ... x 100)

= 1x 101/ 100 x 2

= 101/200

tích nha

=101/200,ai vô k cho tui nha

  1x5+2x6+3x7+4x8+...+50x54

=(1+2+3+4+...50)x(5+6+7+78+...+54)

=1275x1269=1617975

bạn tính vế trái,vế phải ra thì có:

33<x+2<35

x+2=34

x=32

mk chắc chắn với bn là x bằng 32

k mk nha

\(\frac{3}{4}\times\frac{8}{5}\times\frac{5}{9}=\frac{3\times8\times5}{4\times5\times9}=\frac{3\times4\times2\times5}{4\times5\times3\times3}=\frac{2}{3}\)

\(\frac{3}{4}\times\frac{8}{5}\times\frac{5}{9}=\frac{3\times8\times5}{4\times5\times9}=\frac{3\times4\times2\times5}{4\times5\times3\times3}=\frac{2}{3}\)

= 3/4 x 8/9 x 15/16 x ... x 9999/10000

= 3 x 8 x 15 x ... x 9999/ 4 x 9 x 16 x ... x 10000

= (1 x 3) x (2 x 4) x (3 x 5) x ... x (99 x 101)/ (2 x 2) x (3 x 3) x (4 x 4) x ... x (100 x 100)

= (1 x 2 x 3 x ... x 99) x (3 x 4 x 5 x ... x 101)/ (2 x 3 x 4 x ... x 100) x (2 x 3 x 4 x ... x 100)

= (1 x 2 x 3 x ... x 99) x (3 x 4 x 5 x ... x 101)/ (2 x 3 x 4 x ... x 100) x (2 x 3 x 4 x ... x 100)

= 1x 101/ 100 x 2

= 101/200

CHÚC BN HOK TỐT ^^

TA CÓ ;

\(A=\frac{3}{4}.\frac{8}{9}...\frac{2499}{2500}\)

\(A=\frac{1.3}{2.2}.\frac{2.4}{3.3}...\frac{49.51}{50.50}\)

\(A=\frac{1.3.2.4...49.51}{2.2.3.3...50.50}\)

\(A=\frac{\left(1.2...49\right).\left(3.4...51\right)}{\left(2.3...50\right).\left(2.3...50\right)}\)

\(A=\frac{1.51}{50.2}=\frac{51}{100}\)

VẬY \(A=\frac{51}{100}\)