a) x + X x 1,5 + X x 2,5 = 3,75

X x( 1 +1,5 +2,5 ) = 3,75

X x 5 = 3,75

x= 3,75 : 5

x= 0,75 

b) X x 3 +x: 5 = 6,4 

X x 3 + x x 0,2 = 6, 4

X x( 3 + 0,2) = 6,4

X x 3,2 = 6,4 

x= 6,4 : 3,2 

x= 2

xx la nhan hay la so tu nhien vay ban

mình nghĩ là x nhân với

a)  8,8 : 2,5 + 7,6 : 2,5 - 6,4 : 2,5

= (8,8 + 7,6 - 6,4) : 2,5

= 10 : 2,5

= 4

\(a.\)

\(8.8:2.5+7.6:2.5-6.4:2.5\)

\(=\left(8.8+7.6-6.4\right):2.5\)

\(=10:2.5\)

\(=4\)

\(b.\)

\(0.25\times1200+125\times1.5\times2-250\times2.6\)

\(=250\times1.2+250\times1.5-250\times2.6\)

\(=250\times\left(1.2+1.5-2.6\right)\)

\(=250\times0.1=25\)

\(c.\)

\(\left(32\times11-3200\times0.1-32\right):\left(81.6\times27.3-17.3\times81.6\right)\)

\(=\left[32\times\left(11-10-1\right)\right]:\left[81.6\times\left(27.3-17.3\right)\right]\)

\(=0\)

\(x\times6,4=14,3-8+38,6\\ x\times6,4=44,9\\ x=44,9:6,4\\ x=7,015625\)

\(92,6-\left(x+25,8\right)=37,04\\ x+25,8=92,6-37,04\\ x+25,8=55,56\\ x=55,56-25,8\\ x=29,76\)

Th1
x-1,5+2,5-x=0
<=>0x=-1
=> vô lí
Th2
-x+1,5-2,5+x=0
<=>0x=1
=>vô lí

vậy không có x thỏa mãn

x = 4/5 : 3/4

x = 16/15

x = 5/9 : 8/3

x = 5/9 x 3/8

x = 5/24

\(x=\dfrac{4}{5}\times\dfrac{4}{3}\)

\(x=\dfrac{16}{15}\)

-----------------------

\(x=\dfrac{5}{9}\times\dfrac{3}{8}\)

\(x=\dfrac{5}{24}\)

\(x\times\dfrac{3}{4}=\dfrac{4}{5}\)

\(x=\dfrac{4}{5}:\dfrac{3}{4}\)

\(x=\dfrac{4}{5}\times\dfrac{4}{3}\)

\(x=\dfrac{16}{15}\)

\(\dfrac{5}{9}:x=\dfrac{8}{3}\)

      \(x=\dfrac{5}{9}:\dfrac{8}{3}\)

      \(x=\dfrac{5}{9}\times\dfrac{3}{8}\)

     \(x=\dfrac{15}{72}\)

    \(x=\dfrac{5}{24}\)

\(\left[{}\begin{matrix}x-1,5=0\\2,5-x=0\end{matrix}\right.\left[{}\begin{matrix}x=1,5\\x=2,5\end{matrix}\right.\)

\(\left[{}\begin{matrix}x-\dfrac{4}{5}=\dfrac{3}{4}\\x-\dfrac{4}{5}=\dfrac{-3}{4}\end{matrix}\right.\left[{}\begin{matrix}x=\dfrac{31}{20}\\x=\dfrac{1}{20}\end{matrix}\right.\)

c.x thuộc tập hợp rỗng

d. cậu chia ra thành 2 trường hợp nhé

27*18*15=7290

3.8*2.5*4=38

1.9*1.4*1.5=3.99

\(\frac{4}{3}x\frac{5}{4}x\frac{2}{3}=\frac{10}{9}\)

15.5*6.4*10=992

1.75*0.4*0.8=0.56

8*5*4.5=180

2*0.5*0.75=0.75

(15-12)*10.5*8=252

10*4.5*12=540

= 7290

= 38

= 3,99

= 10 / 9

= 992

= 0,56

= 180

= 0,75

= 252

= 540

\(a,\frac{1}{3}+\frac{6}{11}.\frac{22}{5}-\frac{3}{4}:1,5=\frac{1}{3}+\frac{6.2}{5}-\frac{3}{4}:\frac{3}{2}=\frac{1}{3}+\frac{12}{5}-\frac{1}{2}=\frac{10}{30}+\frac{72}{5}-\frac{15}{30}=\frac{67}{30}\)

\(b, 3.3,5.6+2.6,4.9+1,8=18.3,5+18.6,4+1,8=18\left(3,5+6,4\right)+1,8=18.9,9+1,8=1,8.99+1,8=1,8\left(1+99\right)=1,8.100=180\)

b ) 3 x 3,5 x 6 + 2 x 6,4 x 9 + 1,8 

= 18 x 3,5 + 18x 6,4 + 18 x 0,1 

= 18 ( 3,5 + 6,4 + 0,1)

= 18 x 10 

= 180 

1,5 x 3 + 2,5 x 3 + 3,5 x 3 + 4,5 x 5

= 1,5 x 3 + 2,5 x 3 + 3,5 x 3 + 3 x 7,5

= 3 x (1,5 + 2,5 + 3,5 + 7,5)

= 3 x 15

= 45

1,5 x 3 + 2,5 x 3 + 3,5 x 3 + 4,5 x 5

= 1,5 x 3 + 2,5 x 3 + 3,5 x 3 + 3 x 1,5 x 5

= 1,5 x 3 + 2,5 x 3 + 3,5 x 3 + 3 x 7,5

= 3 x ( 1,5 + 2,5 + 3,5 + 7,5 )

= 3 x 15

= 45

1,5 x 3 + 2,5 x 3 + 3,5 x 3 + 4,5 x 5 

= 3 x ( 1,5 + 2,5 + 3,5 ) + 4,5 x 5 

= 3 x 7,5 + 4,5 x 5 

= 22,5   +     22,5

=  45