ĐKXĐ: \(x\ge3\)

\(\Leftrightarrow\sqrt{x-3}=2\sqrt{x^2-9}\)

\(\Leftrightarrow x-3=4\left(x-3\right)\left(x+3\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}x-3=0\\4\left(x+3\right)=1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{11}{4}\left(loại\right)\end{matrix}\right.\)

\(\frac{x}{9}=\frac{8}{x+1}\)ĐK : \(x\ne-1\)

\(\Leftrightarrow x^2+x=72\Leftrightarrow x^2+x-72=0\)

\(\Leftrightarrow\left(x-8\right)\left(x+9\right)=0\)

TH1 : \(x-8=0\Leftrightarrow x=8\)

TH2 : \(x+9=0\Leftrightarrow x=-9\)

\(ĐKXĐ:x\ne-1\)

\(\frac{x}{9}=\frac{8}{x+1}\)\(\Leftrightarrow x\left(x+1\right)=9.8\)

\(\Leftrightarrow x^2+x=72\)\(\Leftrightarrow x^2+x-72=0\)

\(\Leftrightarrow\left(x^2-8x\right)+\left(9x-72\right)=0\)

\(\Leftrightarrow x\left(x-8\right)+9\left(x-8\right)=0\)

\(\Leftrightarrow\left(x-8\right)\left(x+9\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-8=0\\x+9=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=8\\x=-9\end{cases}}\)( thỏa mãn ĐKXĐ )

Vậy \(x=8\)hoặc \(x=-9\)

2/9:2/9x1

=1x1

=1

nha

  \(\frac{2}{9}:\frac{2}{9}\times1\)

\(=1\times1\)

\(=1\)

= 1 nha

3: Ta có: \(\sqrt{4x+1}=x+1\)

\(\Leftrightarrow x^2+2x+1=4x+1\)

\(\Leftrightarrow x\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(nhận\right)\\x=2\left(nhận\right)\end{matrix}\right.\)

4: Ta có: \(2\sqrt{x-1}+\dfrac{1}{3}\sqrt{9x-9}=15\)

\(\Leftrightarrow3\sqrt{x-1}=15\)

\(\Leftrightarrow x-1=25\)

hay x=26

5: Ta có: \(\sqrt{4x^2-12x+9}=7\)

\(\Leftrightarrow\left|2x-3\right|=7\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=7\\2x-3=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=10\\2x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)

\(a,\frac{62}{7}:x=\frac{29}{9}:\frac{3}{56}\)

\(\frac{62}{7}:x=\frac{1624}{27}\)

\(x=\frac{62}{7}:\frac{1624}{27}=\frac{837}{5684}\)

\(b,\frac{1}{5}:x=\frac{1}{5}-\frac{1}{7}\)

\(\frac{1}{5}:x=\frac{2}{35}\)

\(x=\frac{1}{5}:\frac{2}{35}=\frac{7}{2}\)

\(c,\frac{2}{3}.x-\frac{4}{7}=\frac{1}{7}\)

\(\frac{2}{3}.x=\frac{1}{7}+\frac{4}{7}=\frac{5}{7}\)

\(x=\frac{5}{7}:\frac{2}{3}=\frac{15}{14}\)

\(d,\frac{2}{7}-\frac{8}{9}.x=\frac{2}{3}\)

\(\frac{8}{9}.x=\frac{2}{7}-\frac{2}{3}=-\frac{8}{21}\)

\(x=-\frac{8}{21}:\frac{8}{9}=-\frac{3}{7}\)

\(e,\frac{4}{7}+\frac{5}{9}:x=\frac{1}{5}\)

\(\frac{5}{9}:x=\frac{1}{5}-\frac{4}{7}=-\frac{13}{35}\)

\(x=\frac{5}{9}:-\frac{13}{35}=\frac{175}{117}\)

\(i,\frac{2}{5}-\frac{2}{5}.x=\frac{2}{5}\)

\(\frac{2}{5}.\left(1-x\right)=\frac{2}{5}\)

\(1-x=\frac{2}{5}:\frac{2}{5}=1\)

\(x=1-1=0\)

\(g,\frac{2}{3}+\frac{1}{3}:x=-1\)

\(\frac{1}{3}:x=-1-\frac{2}{3}=-\frac{5}{3}\)

\(x=\frac{1}{3}:-\frac{5}{3}=-\frac{1}{5}\)

học tốt nha

Đề viết thiếu ko vậ?

#)Giải :

     \(\frac{2}{9}.\frac{5}{17}+\frac{2}{9}.\frac{13}{17}-\frac{2}{9}.\frac{1}{17}+2018\frac{7}{9}\)

\(=\frac{2}{9}\left(\frac{5}{17}+\frac{13}{17}-\frac{1}{17}\right)+2018\frac{7}{9}\)

\(=\frac{2}{9}.1+2018\frac{7}{9}\)

\(=\frac{2}{9}+2018\frac{7}{9}\)

\(=2018\frac{9}{9}=2019\)

             #~Will~be~Pens~#

\(\frac{2}{9}\times\frac{5}{17}+\frac{2}{9}\times\frac{13}{17}-\frac{2}{7}\times\frac{1}{17}+2018\frac{7}{9}\)

\(=\frac{2}{9}\times\left(\frac{5}{17}+\frac{13}{17}-\frac{1}{17}\right)+2018\frac{7}{9}\)

\(=\frac{2}{9}\times1+2018\frac{7}{9}\)

\(=\frac{2}{9}+2018\frac{7}{9}\)

\(=\frac{2}{9}+2018+\frac{7}{9}\)

\(=\left(\frac{2}{9}+\frac{7}{9}\right)+2018\)

\(=1+2018=2019\)

~ Hok tốt ~

LỚP 6 ĐÂY HẢ BN

có ai pik làm ko

cs tui bt

\(\frac{x-1}{4}=\frac{9}{x^6-1}\)ĐK : \(x\ne\pm1\)

\(\Leftrightarrow\left(x-1\right)\left(x^6-1\right)=36\)

\(\Leftrightarrow x=1\)

Quên xét ĐKXĐ : Vậy vô nghiệm.

cảm ơn bạn nhez

a) -12/27 = 3x-1/9

=> (-12).9 = 27.(3x-1)

=> -108 = 81x-27

=> 81x = -81

=>x=-1

Vậy x=-1.

b) 3-x/45 = 2/9 = 1/2y 

=> 1) 3-x/45 = 2/9

=> 9(3-x)=45.2

=> 27-9x=90

=> 9x=-63

=> x=-7.

2) 2/9=1/2y

=> 2(2y)=9.1

=> 4.2y = 9

=> 2y = 9/4

=> y = 9/8

Vậy x=-7 ; y=9/8

 ~Hok tốt~

Tìm x sao lại có y

-12/27=3x-1/9
3x-1/9=-12/27
3x      =-12/27 + 1/9
3x      = -12/27 + 3/27
3x      = -9/27 = -1/3
x        = -1/3 : 3
x        = -1/9