\(\frac{-9}{x}=\frac{-x}{\frac{4}{49}}\)

=> \(x\left(-x\right)=\left(-9\right)\frac{4}{49}\)

=> \(-x^2\)\(=\frac{-36}{49}\)

=> \(x^2=\frac{36}{49}\)

=> \(x=\frac{6}{7}\)

\(\frac{-9}{x}=\frac{-x}{\frac{4}{49}}\)

\(\Rightarrow x^2=\left(-9\right)\left(\frac{-4}{49}\right)\)

\(\Rightarrow x^2=\frac{36}{49}\)

\(\Rightarrow x=\sqrt{\frac{36}{49}}\)

\(\Rightarrow x=\frac{\sqrt{36}}{\sqrt{49}}\)

\(\Rightarrow x=\frac{\sqrt{6^2}}{\sqrt{7^2}}\)

\(\Rightarrow x=\frac{6}{7}\)

vay \(x=\frac{6}{7}\)

\(\Leftrightarrow x^2=9\times\frac{4}{49}\)

\(\Leftrightarrow x^2=\frac{36}{49}\)

\(\Leftrightarrow x^2=\left(\frac{3}{7}\right)^2\)

\(\Rightarrow x=\frac{3}{7}\)

Ta có : 

\(\frac{x+1}{49}+\frac{x+2}{48}+\frac{x+3}{47}+\frac{x+4}{46}+\frac{x+5}{45}=-5\)

\(\Leftrightarrow\)\(\left(\frac{x+1}{49}+1\right)+\left(\frac{x+2}{48}+1\right)+\left(\frac{x+3}{47}+1\right)+\left(\frac{x+4}{46}+1\right)+\left(\frac{x+5}{45}+1\right)=-5+5\)

\(\Leftrightarrow\)\(\frac{x+50}{49}+\frac{x+50}{48}+\frac{x+50}{47}+\frac{x+50}{46}+\frac{x+50}{45}=0\)

\(\Leftrightarrow\)\(\left(x+50\right)\left(\frac{1}{49}+\frac{1}{48}+\frac{1}{47}+\frac{1}{46}+\frac{1}{45}\right)=0\)

Vì \(\frac{1}{49}+\frac{1}{48}+\frac{1}{47}+\frac{1}{46}+\frac{1}{45}\ne0\)

Nên \(x+50=0\)

\(\Rightarrow\)\(x=-50\)

Vậy \(x=-50\)

Chúc bạn học tốt ~ 

a) x/-27=-3/x

suy ra: x.x=-3.(-27)

suy ra: x^2=81. Suy ra: x^2=9^2 hoặc (-9)^2

suy ra: x=9 hoặc x=-9

Vậy x=9 hoặc x=-9

\(\frac{x}{-27}=\frac{-3}{x}\)=>x²=(-27).(-3)=81

=>x=-9 hoặc x=9

\(\frac{-9}{x}=\frac{4}{49}\)=>4x=(-9).49=441

=> x = 441:4

=> x = 441/4

câu đầu bạn làm đúng rồi nhưng câu sau bạn làm sai , mink nghĩ ra kết quả là 42 là đúng nhưng lại ko bít cách làm

\(-\frac{9}{x}=-\frac{x}{\frac{9}{49}}\)

<=> x.x = \(-9.\left(-\frac{9}{49}\right)\)

<=> x² = \(\frac{81}{49}\) = \(\left(\frac{9}{7}\right)^2\)= \(\left(-\frac{9}{7}\right)^2\)

=> x = + \(\frac{9}{7}\)

Chứng minh rằng (9^2n+1994^93)chia heets cho 5

a) \(x\cdot\frac{1}{2}+x\cdot\frac{1}{4}+x\cdot\frac{1}{8}=\frac{21}{24}\)

\(x\cdot\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}\right)=\frac{7}{8}\)

\(x\cdot\frac{7}{8}=\frac{7}{8}\)

\(\Rightarrow x=\frac{7}{8}\div\frac{7}{8}=1\)

b) \(\left(x+4\right)+\left(x+9\right)+\left(x+14\right)+.....+\left(x+44\right)+\left(x+49\right)=1430\)

\(\left(x+x+x+....+x+x\right)+\left(4+9+14+...+44+49\right)=1430\)

\(10x+265=1430\)

\(10x=1430-265\)

\(10x=1165\)

\(\Rightarrow x=\frac{1165}{10}=116,5\)

c) \(x\cdot0,25-0,5=1\)

\(x\cdot0,25=1+0,5\)

\(x\cdot0,25=1,5\)

\(\Rightarrow x=1,5\div0,25=6\)

\(\left(x+\frac{3}{2}\right)^2=\frac{9}{49}\)

\(\Rightarrow\left(x+\frac{3}{2}\right)^2=\left(\frac{3}{7}\right)^2\)

\(\Rightarrow x+\frac{3}{2}=\frac{3}{7}\)

\(\Rightarrow x=\frac{3}{7}-\frac{3}{2}\)

\(\Rightarrow x=\frac{-15}{14}\)

Vậy  \(x=\frac{-15}{14}\)

_Chúc bạn học tốt_

(x+3/2)²=9/49

x+3/2=3/7

X=3/7-3/2

x=6-21/14

x=-15/14

\(\left(x+\frac{3}{2}\right)^2=\frac{9}{49}\)

\(\left(x+\frac{3}{2}\right)^2=\frac{3}{7}^2\)

        \(x+\frac{3}{2}=\frac{3}{7}\)

                   \(x=\frac{3}{7}-\frac{3}{2}\)

                   \(x=\frac{6}{14}-\frac{21}{14}\)

                  \(x=\frac{6-21}{14}\)

                 \(x=-15\)

Đúng thì tk nha , sai đừng anti , mơn nhìu !!!
~ HOK TỐT ~

\(\frac{-9}{x}=\frac{-x}{\frac{4}{49}}\)

\(\Rightarrow x^2=-9.\left(\frac{-4}{49}\right)\)

\(\Rightarrow x^2=\frac{36}{49}\)

\(\Rightarrow x=\sqrt{\frac{36}{49}}\)

\(\Rightarrow x=\sqrt{\frac{6^2}{7^2}}\)

\(\Rightarrow x=\sqrt{\left(\frac{6}{7}\right)^2}\)

\(\Rightarrow x=\frac{6}{7}\)

vay \(x=\frac{6}{7}\)

\(\frac{-9}{x}=\frac{-x}{\frac{4}{49}}\)

-9 x\(\frac{4}{49}\)=\(x\times\left(-x\right)\)

\(-\frac{36}{49}\)= -2x

\(\Rightarrow\)2x=\(\frac{36}{49}\)( cùng bớt dấu âm của 2 vế)

x=\(\frac{36}{49}:2\)

x=\(\frac{18}{49}\)

vậy x = \(\frac{18}{49}\)

th1 \(\left(\frac{3}{4}x-5\right)^2=\left(+-\frac{3}{7}\right)^2\)

suy ra 3/4x-5=3/7

3/4x=3/7+5

3/4x=5/3/7

x=5/3/7:3/4

x=7/5/21

th2 3/4x-5=-3/7

3/4x=-3/7+5

3/4x=4/4/7

x=4/4/7:3/4

x=6/2/21