\(356\times708-708\times256=708\times\left(356-256\right)=708\times100=70800\)

\(\dfrac{3}{22}\times\dfrac{3}{11}\times22=\dfrac{6}{11}\)

159

159

159

\(\dfrac{9}{10}\times2+3\times\dfrac{9}{10}+\dfrac{9}{10}:\dfrac{1}{5}\)

\(=\dfrac{9}{10}\times2+\dfrac{9}{10}\times3+\dfrac{9}{10}\times5\)

\(=\dfrac{9}{10}\times\left(2+3+5\right)\)

\(=\dfrac{9}{10}\times10\)

\(=\dfrac{90}{10}\)

\(=9\)

a) A= \(3x^2 - 2x+1\) với |x| = \(\dfrac{1}{2}\)

Với |x| = \(\dfrac{1}{2}\) \(\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{matrix}\right.\)

Khi \(x=\dfrac{1}{2}\) ⇒ \(A=3.\left(\dfrac{1}{2}\right)^2-2.\dfrac{1}{2}+1=\dfrac{3}{4}-1+1=\dfrac{3}{4}\)

Khi \(x=-\dfrac{1}{2}\) ⇒ \(A=3.\left(-\dfrac{1}{2}\right)^2-2.\left(-\dfrac{1}{2}\right)+1=\dfrac{3}{4}+1+1=\dfrac{3}{4}+2=\dfrac{11}{4}\)

Vậy...

       4/3 x 5/4 x 6/5 x 7/6 x  8/7 x 9/8 

   =  4/9   

( 4/9 + 7/9 -  2/9 ) x 19/24  = 1 x 19/24 = 19/24

\(=\dfrac{19}{24}\times\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{19}{24}\times1=\dfrac{19}{24}\)

\(\dfrac{19}{24}\times\left(\dfrac{4}{9}+\dfrac{7}{9}-\dfrac{2}{9}\right)\)

\(=\dfrac{19}{24}\times1=\dfrac{19}{24}\)

Mọi ng giúp mình nha, minh cần gấp 

5 : 0,5 +18 : 0,25 + 2,25 : 0,125 

= ( 5: 0,5) + (18 : 0,25) + ( 2,25 : 0,125)

= 10 + 72 + 18

= 100

     5 : 0,5 + 8 : 0,25 + 125 : 0,125

=  5 x 2 + 8 x 4 + 125 x 8 

= 10 + 32 + 1000

= 42 + 1000

= 1042 

1042