3/25 x ( 15/7 - 2/7 ) + 3/7 x 1/25 

= 3/25 x 13/7 + 3/7 x 1/25 

= (3 x 13/7 + 3/7 ) x 1/25 

= 42/7 x 1/25 

= 6 x 1/25 

= 6/25

\(\dfrac{3}{25}\times\dfrac{15}{7}+\dfrac{3}{7}\times\dfrac{1}{25}-\dfrac{2}{7}\times\dfrac{3}{25}\)

\(=\dfrac{3}{25}\times\left(\dfrac{15}{7}-\dfrac{2}{7}\right)+\dfrac{3}{7}\times\dfrac{1}{25}\)

\(=\dfrac{3}{25}\times\dfrac{13}{7}+\dfrac{3}{7}\times\dfrac{1}{25}\)

\(=\dfrac{3\times13}{25\times7}+\dfrac{3\times1}{7\times25}\)

\(=\dfrac{39}{175}+\dfrac{3}{175}\)

\(=\dfrac{39+3}{175}\)

\(=\dfrac{42}{175}\)

\(=\dfrac{6}{25}\)

A = \(\dfrac{3}{25}\) \(\times\) \(\dfrac{15}{7}\) + \(\dfrac{3}{25}\) \(\times\) \(\dfrac{1}{7}\) - \(\dfrac{2}{7}\times\) \(\dfrac{3}{25}\)

A = \(\dfrac{3}{25}\) \(\times\)( \(\dfrac{15}{7}\) + \(\dfrac{1}{7}-\dfrac{2}{7}\))

A = \(\dfrac{3}{25}\) \(\times\) \(\dfrac{14}{7}\)

A = \(\dfrac{6}{25}\)

\(\frac{167}{99}\)

25^7*18 - 25^7*13

=25^7*(18-13)

=25^7*5

=(5^2)^7*5

=5^14*5=5^15

k cho mk ***** nha 

đúng rồi đó , la 15^5 , mình thi rùi.

 leminhduc làm gì mk chả hiểu lớp 6 làm gì có căn rồi 

\(1+3+5+......+x=2500\)

\(\Rightarrow\left[\left(x-1\right):2+1\right].\left(x+1\right):2=2500\)

\(\Rightarrow\left(\frac{x}{2}-\frac{1}{2}+1\right).\left(x+1\right)=2500.2\)

\(\Rightarrow\left(\frac{x}{2}+\frac{1}{2}\right).\left(x+1\right)=5000\)

\(\Rightarrow\frac{x^2}{2}+\frac{1}{2}x+\frac{x}{2}+\frac{3}{2}=5000\)

\(\Rightarrow\frac{x^2+x+x+3}{2}=5000\)

\(\Rightarrow x^2+2x+3=5000.2\)

\(\Rightarrow x^2+2x.1+1^2+3-1^2=10000\)

\(\Rightarrow\left(x+1\right)^2+2=10000\)

\(\Rightarrow\left(x+1\right)^2=10000-2\)

\(\Rightarrow\left(x+1\right)^2=9998\)

\(\Rightarrow x+1=\sqrt{9998}\)

\(\Rightarrow x=\sqrt{9998}-1\)

x=99,985

hdsghj

Bài 1 :

a) \(...=5^5:5^4=5\)

b) \(...=7^8:7^9=\dfrac{1}{7}\)

c) \(...=2^{15}:\left(2^6.2^5\right)=2^{15}:2^{11}=2^4=16\)

d) \(...=3^{28}:3^{26}=3^2=9\)

Bài 2 :

a) \(...=3^2.3^3:3^4=3^5:3^4=3\)

b) \(...=10^9-10^9=0\)

c) \(...=5^{10}.5^{30}:5^{12}=5^{40}:5^{12}=5^{28}\)

d) \(...=5^{12}:5^9=5^3=125\)

=8743

x=364x24

x=8736

x=8736+7 

x=8743

x = 364 x 24

x = 8736

x = 8736 + 7 

x = 8743

@꧁ミ〖★ Äŋħ ✔𝕽ҽäӀ✔⁀★〗ミ♪ ᶦᵈᵒᶫ꧂

\(\frac{3}{5}.\left(\frac{5}{3}-\frac{2}{7}\right)-\left(\frac{7}{3}-\frac{3}{7}\right).\frac{3}{5}\)

\(=\frac{3}{5}.\text{[}\left(\frac{5}{3}-\frac{2}{7}\right)-\left(\frac{7}{3}-\frac{3}{7}\right)\text{]}\)

\(=\frac{3}{5}.\text{[}\frac{5}{3}-\frac{2}{7}-\frac{7}{3}+\frac{3}{7}\text{]}\)

\(=\frac{3}{5}.\text{[}\left(\frac{5}{3}-\frac{7}{3}\right)-\left(\frac{2}{7}-\frac{3}{7}\right)\text{]}\)

\(=\frac{3}{5}.\text{[}\frac{-2}{3}-\frac{-1}{7}\text{]}\)

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

\(=\frac{3}{5}.\left(\frac{-14}{21}+\frac{3}{21}\right)\)

\(=\frac{3}{5}.\frac{-11}{21}\)

\(=\frac{3.\left(-11\right)}{5.21}\)

\(=\frac{-11}{5.7}=\frac{-11}{35}\)

Chúc bạn học tốt

Ta có: x : 25 - [ x + 1,85 ] : 3 = 7

=> 25 - [ x + 1,85 ] = 7 x 3

=> 25 - [ x + 1,85 ] = 21

=>        [ x + 1,85 ] = 25 - 21

=>        x + 1,85 = 4

=> x = 4 - 1,85

=> x = 2,15

Ta có: x : 25 - [ x + 1,85 ] : 3 = 7 => 25 - [ x + 1,85 ] = 7 x 3 => 25 - [ x + 1,85 ] = 21 => [ x + 1,85 ] = 25 - 21 => x + 1,85 = 4 => x = 4 - 1,85 => x = 2,15