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

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

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

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

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

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

hay x=2

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 

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

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

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

\(=45,82\times3\)

\(=137,46\)

\(=\dfrac{13}{12}\cdot\dfrac{27}{5}\cdot2\cdot\dfrac{34}{9}\cdot2\cdot\dfrac{2}{17}=4\cdot\dfrac{4}{9}\cdot\dfrac{13}{5}\cdot\dfrac{9}{4}=4\cdot\dfrac{13}{5}=\dfrac{52}{5}\)

Câu 1: D

Câu 2: A

\(\left(1+\dfrac{2}{24}\right)\cdot5=\dfrac{13}{12}\cdot5=\dfrac{65}{12}=\dfrac{195}{36}\)

\(2.5\cdot2\cdot3\dfrac{7}{9}\cdot2\cdot\dfrac{2}{17}\)

\(=10\cdot\dfrac{2}{17}\cdot\dfrac{34}{9}=\dfrac{40}{9}=\dfrac{160}{36}\)

Do đó: 195/36>160/36