A.   7,01 x 4 x 25

     = 7,01 x ( 4 x 25 )

    = 7,01 x 100

    = 701

B.   5 x 250 x 0,2

  = (5 x 0,2) x 250

  = 1 x 250

  =  250

C.   1,25 x 0,29 x 8

= (1,25 x 8 ) x 0,29

= 10 x 0,29

= 2,9

D.   0,04 x 0,1 x 25

= ( 0,04 x 25 ) x 0,1

= 1 x 0,1

=  0,1

a) \(x^5\cdot x^3\cdot x^2=x^{5+3+2}=x^{10}\)

b) \(\left(0,2\right)^8:0,04=\left(0,2\right)^8:\left(0,2\right)^2=\left(0,2\right)^{8-2}=\left(0,2\right)^6\)

CHÚC BẠN HỌC TỐT!!!!!!!!!!!

a)x^5.x^3.x^2=x^5+3+2=x^10

b)0,2^8:0,04=0,2^8:0,2^2=0,2^8-2=0,2^6

Lời giải:

Ta có:

$2(ab+bc+ac)=(a+b+c)^2-(a^2+b^2+c^2)=6^2-12=24=2(a^2+b^2+c^2)$

$\Rightarrow 2(a^2+b^2+c^2)-2(ab+bc+ac)=0$

$\Leftrightarrow (a^2+b^2-2ab)+(b^2+c^2-2bc)+(c^2+a^2-2ac)=0$

$\Leftrightarrow (a-b)^2+(b-c)^2+(c-a)^2=0$

$\Rightarrow a-b=b-c=c-a=0$

$\Rightarrow a=b=c$. Mà $a+b+c=6$ nên $a=b=c=2$

Khi đó:

$A=(2-3)^{2020}+(2-3)^{2020}+(2-3)^{2020}=1+1+1=3$

20/24

31/40

10/3

20/24

31/40

10/3

 a)\(=\dfrac{20}{24}=\dfrac{5}{6}\)

b)\(=\dfrac{31}{40}\)

c)\(=\dfrac{24}{12}+\dfrac{9}{12}+\dfrac{7}{12}=\dfrac{40}{12}=\dfrac{10}{3}\)

\(a,\\ =\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+\left(\dfrac{1}{8}+\dfrac{7}{8}\right)=1+1=2\\ b,\\ =\left(\dfrac{1}{3}+\dfrac{4}{3}+\dfrac{2}{3}\right)\left(\dfrac{5}{12}+\dfrac{1}{12}\right)\\ =\dfrac{7\times2}{3\times2}+\dfrac{1\times3}{2\times3}=\dfrac{14+3}{6}=\dfrac{17}{6}\)

\(a,\dfrac{4}{9}+\dfrac{1}{8}+\dfrac{5}{9}+\dfrac{7}{8}=\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+\left(\dfrac{1}{8}+\dfrac{7}{8}\right)=\dfrac{9}{9}+\dfrac{8}{8}=1+1=2\\ b,\dfrac{1}{3}+\dfrac{2}{3}+\dfrac{5}{12}+\dfrac{4}{3}+\dfrac{1}{12}=\left(\dfrac{1}{3}+\dfrac{2}{3}+\dfrac{4}{3}\right)+\left(\dfrac{5}{12}+\dfrac{1}{12}\right)=\dfrac{7}{3}+\dfrac{6}{12}=\dfrac{7}{3}+\dfrac{1}{2}=\dfrac{14}{6}+\dfrac{3}{6}=\dfrac{17}{6}\)

a: \(=\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+\left(\dfrac{1}{8}+\dfrac{7}{8}\right)\\ =1+1=2\)

b: \(=\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{5}{12}+\dfrac{1}{12}\right)+\dfrac{4}{3}\\ =1+\dfrac{1}{2}+\dfrac{4}{3}=\dfrac{17}{6}\)

250 x 5 x 0,2

= 250 x ( 5 x 0,2 )

= 250 x 1

= 250

0,29 x 8 x 1,25 

= 0,29 x ( 8 x 1,25 )

= 0,29 x 10

= 2,9

0,04 x 0,1 x 25

= ( 0,04 x 25 ) x 0,1 

= 1 x 01

= 0,1

250 x 5 x 0,2 

= 250 x 1

= 250

0,25 x 8 x 1,25

= 0,25 x 10 

= 2,5

0,04 x 0,1 x 25

= 0,04 x 2,5

= 0,1

Tôi có lời khen

B

Đ