9/4;4/5;5/7;7/12;5/12

Em nên gõ công thức trực quan để đề bài rõ ràng nhé

`5030,407`

5030,407

\(-2,5\times\left(x+\dfrac{1}{5}\right)=\dfrac{7}{5}\)

\(\Leftrightarrow x+\dfrac{1}{5}=\dfrac{7}{5}:\left(-2,5\right)\)

\(\Leftrightarrow x+\dfrac{1}{5}=\dfrac{7}{5}\times\left(-\dfrac{2}{5}\right)\)

\(\Leftrightarrow x+\dfrac{1}{5}=-\dfrac{14}{25}\)

\(\Leftrightarrow x=-\dfrac{19}{25}\)

\(-2,5\cdot\left(x+\dfrac{1}{5}\right)=\dfrac{7}{5}\)

\(x+\dfrac{1}{5}=\dfrac{7}{5}:\left(-2,5\right)\)

\(x+\dfrac{1}{5}=\dfrac{7}{5}\times\left(-\dfrac{2}{5}\right)\)

\(x+\dfrac{1}{5}=-\dfrac{14}{25}\)

\(x=-\dfrac{14}{25}-\dfrac{1}{5}\)

\(x=-\dfrac{19}{25}\)

kq=55

=(1+9)+(2+8)+(3+7)+(4+6)+10+5.

=10+10+10+10+10+5=55.

tk mk nha.\chúc các bạn tk mk học giỏi

\(\dfrac{7}{5}+\dfrac{4}{7}-\dfrac{9}{10}=\dfrac{49-20}{35}-\dfrac{9}{10}=\dfrac{19}{35}-\dfrac{9}{10}=\dfrac{190-315}{350}=\dfrac{-125}{350}\)

\(\dfrac{2}{1}+\dfrac{3}{4}\text{×}\dfrac{8}{5}=\dfrac{8+3}{4}\text{×}\dfrac{8}{5}=\dfrac{11\text{×}8}{4\text{×}5}=\dfrac{88}{20}\)

mấy câu kia áp dụng là dc!

Oki

Giúp mình với ạ !! Mình cần gấp lắm . 

hình như là tổng tỉ đấy,

Có: \(\dfrac{\left(-3\right)^{10}x15^5}{25^3x\left(-9\right)^7}=\dfrac{3^{10}.\left(3.5\right)^5x}{-\left(3^2\right)^7\left(5^2\right)^3x}\)

\(=\dfrac{3^{15}.5^5x}{-3^{14}.5^6x}\)\(=\dfrac{3^{14}.5^5\left(3x\right)}{3^{14}.5^5\left(-5x\right)}=\dfrac{3x}{-5x}=-\dfrac{3}{5}\)

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