a) 563 x 23 + 23 x 28 - 23

= 23 x (563 + 28 - 1)

= 23 x 600

= 19200

b) \(\frac{7}{11}+\frac{3}{4}+\frac{4}{11}+\frac{1}{4}-1\frac{2}{5}=\left(\frac{7}{11}+\frac{4}{11}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)-\frac{7}{5}=2-\frac{7}{5}=\frac{3}{5}\)

c) \(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times...\times\left(1-\frac{1}{10}\right)=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times....\times\frac{9}{10}\)

\(=\frac{1\times2\times3\times...\times9}{2\times3\times4\times...\times10}=\frac{1}{10}\)

d) \(\frac{2}{7}\times\frac{3}{9}+\frac{2}{7}\times\frac{2}{3}=\frac{2}{7}\times\left(\frac{3}{9}+\frac{2}{3}\right)=\frac{2}{7}\times1=\frac{2}{7}\)

a ) \(563\cdot23+23\cdot28-23\)

\(=23\cdot\left(563+28-1\right)\)

\(=23\cdot600\)

\(=19200\)

b ) \(\frac{7}{11}+\frac{3}{4}+\frac{4}{11}+\frac{1}{4}-1\frac{2}{5}=\left(\frac{7}{11}+\frac{4}{11}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)-\frac{7}{5}=2-\frac{7}{5}=\frac{3}{5}\)

c ) \(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{10}\right)=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot...\cdot\frac{9}{10}\)

\(=\frac{1\cdot2\cdot3\cdot...\cdot9}{2\cdot3\cdot4\cdot...\cdot10}=\frac{1}{10}\)

d ) \(\frac{2}{7}\cdot\frac{3}{9}+\frac{2}{7}\cdot\frac{2}{3}=\frac{2}{7}\cdot\left(\frac{3}{9}+\frac{2}{3}\right)=\frac{2}{7}\cdot1=\frac{2}{7}\)

Bài 1:

câu a: 4\(\dfrac{4}{9}\) : 2\(\dfrac{2}{3}\) + 3\(\dfrac{1}{6}\)

        = \(\dfrac{40}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{19}{6}\)

        = \(\dfrac{5}{3}\) + \(\dfrac{19}{6}\)

         = \(\dfrac{10}{6}\) + \(\dfrac{19}{6}\)

          = \(\dfrac{29}{6}\)

b, (15,25 + 3,75) \(\times\) 4 + ( 20,71 + 5,29)\(\times\) 5

     = 19 \(\times\) 4 + 26 \(\times\) 5

     = 76 + 130

     = 206

c, \(\dfrac{4}{5}\) \(\times\) \(\dfrac{1}{2}\) + \(\dfrac{4}{5}\) \(\times\) \(\dfrac{1}{3}\) - \(\dfrac{4}{5}\) \(\times\) \(\dfrac{1}{4}\)

= \(\dfrac{2}{5}\)    + \(\dfrac{4}{15}\) - \(\dfrac{1}{5}\)

= \(\dfrac{6}{15}\) + \(\dfrac{4}{15}\) - \(\dfrac{3}{15}\)

= \(\dfrac{7}{15}\) 

d, 1\(\dfrac{5}{7}\) + 7\(\dfrac{3}{6}\) + 2\(\dfrac{2}{7}\) - 4\(\dfrac{3}{6}\)

= (1 + 2 + \(\dfrac{5}{7}\) + \(\dfrac{2}{7}\)) + ( 7 + \(\dfrac{3}{6}\) - 4 - \(\dfrac{3}{6}\))

=  3 + 1 + 3 

= 7

e, 8,4 \(\times\) \(x\) + 1,6 \(\times\) \(x\) = 10

   (8,4 + 1,6) \(\times\) \(x\)      = 10

     10 \(\times\) \(x\)                = 10

               \(x\)                = 1

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

=7x9

=63

7x3+7x2+7x3+7

= 7x (3+2+3+7)

= 7x 15

= 105

7 x 3 + 7 x 2 + 7 x 3 + 7

7 x 3 + 7 x 2 + 7 x 3 + 7 x 1

= 7 x ( 3 + 2 + 3 + 1 ) 

= 7 x 9 

= 63

Chúc bạn học tốt !

4/5

4/5

\(\dfrac{6}{7}x\dfrac{2}{3}x\dfrac{7}{5}=\dfrac{4}{5}\)

bằng 1/2 nha

Lời giải:
$A(x)+B(x)=5-3x^2+2x-5x^3+6x+7x^3-7x^2-9$

$=2x^3-10x^2+8x-4$

$A(x)-B(x)=(5-3x^2+2x-5x^3)-(6x+7x^3-7x^2-9)$

$=-12x^3+4x^2-4x+14$

 a)\(\left(\dfrac{5}{6}+\dfrac{3}{8}\right)\times\dfrac{2}{7}\)

\(=\dfrac{29}{24}\times\dfrac{2}{7}\)

\(=\) \(\dfrac{29}{84}\)

b) \(\dfrac{6}{7}\times\dfrac{2}{3}\div\dfrac{5}{7}\)

= \(\dfrac{4}{7}\div\) \(\dfrac{5}{7}\)

= \(\dfrac{4}{5}\)

c) \(\dfrac{8}{9}+\dfrac{3}{4}\times\dfrac{4}{9}\)

= \(\dfrac{8}{9}+\dfrac{1}{3}\)

= \(\dfrac{5}{9}\)

Cô tích xanh cho lisa blackpink vì câu a, b đúng. Còn câu c thì em làm như sau:

c, \(\dfrac{8}{9}\) + \(\dfrac{3}{4}\) \(\times\) \(\dfrac{4}{9}\) 

  = \(\dfrac{8}{9}\) + \(\dfrac{1}{3}\)

  =  \(\dfrac{8}{9}\) + \(\dfrac{3}{9}\)

  =    \(\dfrac{11}{9}\)

a) 29/84

b) 4/5

c) 5/9

giúp mình với mình sắp thi giữa kì rồi