9*9,8-2,5+9,8*9-9+2,5*8-2-6*2:3 

=88,2-2,5+88,2-9+20-2-6*2:3 

=88,2-2,5+88,2-9+20-2-4 

=85,7+88,2-9+20-2-4 

=173,9-9+20-2-4 

=164,9+20-2-4 

=184,9-2-4 

=182,9-4 

=178,9

Haiz phải là : 9 x 9,8 - 2,5 + 9,8 x 9 - 9 + 2,5 x 8 -2 - 6 x 2 : 3

= 9,8 x ( 9 + 9 + 9 - 9 ) - 2,5 x 8 - 2 - 6 x 2 : 3

= 9,8 x ( 9 + 9 + 9 - 9 ) - 2,5 x 8 - 2

= 9,8 x 18 - 2,5 x 8 - 2 

= 176,4 - 20 - 2 = ( 176,4 - 20 ) -2 = 156,4 - 2 = 154,4          Thật ra là tự tính chứ không chắc ( "0 u 0")

a ta co xét ti le xích  1/3=4/12 nhan hai ti so cua ti le thức với  3*12 ta dược 1/3*(3*12)=4/12*(3*12)=>1*12=4*3

Cung de Ma Nho tích cho minh nha con cau b chua lam thong cảm

hãy tự tin vào chính bản thân

tui cũng hỏi giống bạn nhưng không ai giai cho tui cả huhu

a: \(\Leftrightarrow\left(x-\dfrac{2}{5}\right):\dfrac{3}{2}=-\dfrac{5}{4}+\dfrac{5}{2}=\dfrac{5}{4}\)

\(\Leftrightarrow x-\dfrac{2}{5}=\dfrac{5}{4}\cdot\dfrac{3}{2}=\dfrac{15}{8}\)

hay x=91/40

b: \(\Leftrightarrow\left(2.5x-3.6\right)=-1\cdot\dfrac{12}{7}=\dfrac{-12}{7}\)

=>2,5x=66/35

hay x=132/175

c: \(\Leftrightarrow\left(\dfrac{15}{4}-2x\right)=\dfrac{19}{9}:\dfrac{4}{3}=\dfrac{19}{9}\cdot\dfrac{3}{4}=\dfrac{19}{12}\)

=>2x=15/4-19/12=45/12-19/12=26/12

=>x=13/12

\(x-\dfrac{9}{2}=-2,5\)

\(x-\dfrac{9}{2}=-\dfrac{5}{2}\)

\(x=\dfrac{-5}{2}+\dfrac{9}{2}\)

\(x=2\)

\(x-\dfrac{9}{2}=2,5\)

\(\Rightarrow7\)

\(x-\dfrac{9}{2}=-\dfrac{2}{5}\Leftrightarrow x=-\dfrac{2}{5}+\dfrac{9}{2}=\dfrac{41}{10}\)

đề như z ak bn!

a)*  3x =26

=> x = 26/3

* 3x = 6

=> x = 2

b) \(x:4\times\frac{1}{3}=2,5\)

\(x\times\frac{1}{4}\times\frac{1}{3}=2,5\)

\(x\times\frac{1}{12}=2,5\)

\(x=2,5:\frac{1}{12}\)

\(x=30\)

c) \(\frac{3}{4x}=\frac{1}{2}=\frac{3}{6}\)

\(\Rightarrow\frac{3}{4x}=\frac{3}{6}\)

\(\Rightarrow4x=6\)

\(x=6:4\)

\(x=\frac{3}{2}\)

nếu như đề mk viết sai thì nhắn lại cho mk, mk sửa nha!

x=1,5 bạn nhé

45,82 x 9 - 45,82 x2 x2,5 - 45.82

=45,82 x 9 - 45.82 x 5  -45,82 ,82

= 45,82 x ( 9 - 5 - 1)

=45,82 x 3

=137,46

= 45,82 x 9 - 45,82 x 5 - 45,82 x 1 

= 45,82 x ( 9 - 5 - 1 ) 

= 45,82 x 3 

= 137,46 

\(45,82\times9-45,82\times2,5\times2-45,82\)

\(=45,82\times9-45,82\times5-45,82\)

\(=45,82\times\left(9-5-1\right)\)

\(=45,82\times3\)

\(=137,46\)

\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)

\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)

\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)

\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)

bài 2

\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)

b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)

Bài 1: 

a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)

\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)

b) \(30.96-6.45+14.4:3=24.51+4.8=29.33\)

\(\dfrac{2}{5}\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\left(\dfrac{8}{10}-\dfrac{5}{10}\right)=\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{6}{50}=\dfrac{3}{25}\)