`a)` `2/5 + 3/5 xx 4/9 - 1/3`

`= 2/5 + 4/15 - 1/3`

`= 6/15 + 4/15 - 5/15`

`= 1/3`

`b)` `( 5/2 - 1/3 ) xx 9/2 - 1/2`

`= ( 15/6 - 2/6 ) xx 9/2 - 1/2`

`= 13/6 xx 9/2 - 1/2`

`= 39/4 - 2/4`

`= 37/4`

-6/35

1/5x (4/7- 3/7- 1)=1/5x -6/7= -6/35

\(-\dfrac{6}{35}\)

\(\dfrac{1}{5}\times\dfrac{4}{7}+\dfrac{3}{7}\times\dfrac{1}{5}-\dfrac{1}{5}\)

\(=\dfrac{4}{35}+\dfrac{3}{35}-\dfrac{1}{5}\)

\(=\dfrac{7}{35}-\dfrac{1}{5}\)

\(=\dfrac{1}{5}-\dfrac{1}{5}\)

\(=0\)

0

(Dấu . là dấu nhân)
a/\(\dfrac{2}{5}\cdot\dfrac{4}{3}-\dfrac{2}{5}:3\)
\(=\dfrac{2}{5}\cdot\dfrac{4}{3}-\dfrac{2}{5}\cdot\dfrac{1}{3}\)
\(=\dfrac{2}{5}\cdot\left(\dfrac{4}{3}-\dfrac{1}{3}\right)\)
\(=\dfrac{2}{5}\cdot1\)
\(=\dfrac{2}{5}\)
b/\(\dfrac{2010}{2018}:\dfrac{1}{2}+\dfrac{7}{2018}:\dfrac{1}{2}\)
\(=\left(\dfrac{2010}{2018}+\dfrac{7}{2018}\right):\dfrac{1}{2}\)
\(=\dfrac{2017}{2018}:\dfrac{1}{2}\)
\(=\dfrac{2017}{2018}\cdot2\)
\(=\dfrac{2017}{1009}\)

a, \(\dfrac{2}{5}\) \(\times\) \(\dfrac{4}{3}\) - \(\dfrac{2}{5}\) : 3

=  \(\dfrac{2}{5}\) \(\times\) \(\dfrac{4}{3}\) - \(\dfrac{2}{5}\) \(\times\) \(\dfrac{1}{3}\)

= \(\dfrac{2}{5}\) \(\times\) ( \(\dfrac{4}{3}\) - \(\dfrac{1}{3}\))

= \(\dfrac{2}{5}\)  \(\times\) 1

= \(\dfrac{2}{5}\) 

b, \(\dfrac{2010}{2018}\) : \(\dfrac{1}{2}\) + \(\dfrac{7}{2018}\) : \(\dfrac{1}{2}\) + \(\dfrac{1}{2018}\) : \(\dfrac{1}{2}\)

= \(\dfrac{2010}{2018}\) \(\times\) \(\dfrac{2}{1}\) + \(\dfrac{7}{2018}\) \(\times\) \(\dfrac{2}{1}\) + \(\dfrac{1}{2018}\) \(\times\) \(\dfrac{2}{1}\)

= \(\dfrac{2}{1}\) \(\times\) ( \(\dfrac{2010}{2018}\) + \(\dfrac{7}{2018}\) + \(\dfrac{1}{2018}\))

= 2 \(\times\) \(\dfrac{2018}{2018}\)

= 2 \(\times\) 1

= 2

a) C1:

= 11/10 x 4/5 = 44/50 = 22/25

C2:

= 3/5 x 4/5 + 1/2 x 4/5 = 12/25 + 2/5 = 22/25

b) C1:

= 2/5 x (3/7 + 4/7) = 2/5 x 1 = 2/5

C2:

= 6/35 + 8/35 = 14/35 = 2/5

a)(3/5+1/2)x4/5

= \(\left(\dfrac{6}{10}+\dfrac{5}{10}\right)\times\dfrac{4}{5}=\dfrac{11}{10}\times\dfrac{4}{5}=\dfrac{22}{25}\)

\(=\dfrac{3}{5}\times\dfrac{4}{5}+\dfrac{1}{2}\times\dfrac{4}{5}=\dfrac{12}{25}+\dfrac{2}{5}=\dfrac{22}{25}\)

b)2/5x3/7+2/5x4/7

\(=\dfrac{6}{35}+\dfrac{8}{35}=\dfrac{14}{35}=\dfrac{2}{5}\)

\(=\dfrac{2}{5}\times\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\times1=\dfrac{2}{5}\)

\(\)

vvvvvvvvvvvvvvvv

8/13+4/9+1/3+5/13+3=

(8/13+5/13)+(4/9+3/9)+3=

1+7/9+3=4 7/9

8/5x4/7+4/7x2/5=

4/7x(8/5+2/5)

=4/7x2=8/7

a) kết quả bằng  43/9

b) hiện tại chưa tính ra

Đáp án đúng: B. 5 040 321

B. 5040321

c) Ta có: \(\dfrac{5x^4+9x^3-2x^2-4x-8}{x-1}\)

\(=\dfrac{5x^4-5x^3+14x^3-14x^2+12x^2-12x+8x-8}{x-1}\)

\(=\dfrac{5x^3\left(x-1\right)+14x^2\left(x-1\right)+12x\left(x-1\right)+8\left(x-1\right)}{x-1}\)

\(=5x^3+14x^2+12x+8\)

d) Ta có: \(\dfrac{5x^3+14x^2+12x+8}{x+2}\)

\(=\dfrac{5x^3+10x^2+4x^2+8x+4x+8}{x+2}\)

\(=\dfrac{5x^2\left(x+2\right)+4x\left(x+2\right)+4\left(x+2\right)}{x+2}\)

\(=5x^2+4x+4\)

c) Ta có: \(\dfrac{5x^4+9x^3-2x^2-4x-8}{x-1}\)

\(=\dfrac{5x^4-5x^3+14x^3-14x^2+12x^2-12x+8x-8}{x-1}\)

\(=\dfrac{5x^3\left(x-1\right)+14x^2\left(x-1\right)+12x\left(x-1\right)+8\left(x-1\right)}{x-1}\)

\(=5x^3+14x^2+12x+8\)