\(\Leftrightarrow\dfrac{16}{x+4}+\dfrac{16}{x-4}=\dfrac{5}{3}\)

=>\(\dfrac{16x-64+16x+64}{x^2-16}=\dfrac{5}{3}\)

=>5(x^2-16)=3*32x=96x

=>5x^2-96x-80=0

=>x=20 hoặc x=-4/5

\(\frac{80}{x+4}+\frac{80}{x-4}=\frac{25}{3}\left(1\right)\)

ĐKXĐ: \(x\ne\pm4\)

\(\left(1\right)\Leftrightarrow\frac{80\left(x-4\right)}{\left(x-4\right)\left(x+4\right)}+\frac{80\left(x+4\right)}{\left(x-4\right)\left(x+4\right)}=\frac{25}{3}\)

\(\Leftrightarrow\frac{80x-320+80x+320}{\left(x-4\right)\left(x+4\right)}=\frac{25}{3}\)

\(\Leftrightarrow\frac{160x}{\left(x-4\right)\left(x+4\right)}=\frac{25}{3}\)

\(\Rightarrow480x=25\left(x-4\right)\left(x+4\right)\)

\(\Leftrightarrow480x=25\left(x^2-16\right)\)

\(\Leftrightarrow480x=25x^2-400\)

\(\Leftrightarrow25x^2-480x-400=0\)

\(\Leftrightarrow25x^2-480x+2304-2704=0\)

\(\Leftrightarrow\left(5x-48\right)^2=2704\)

\(\Leftrightarrow\left|5x-48\right|=52\)

  +Trường hợp 1: Nếu \(x\ge\frac{48}{5}\)thì \(5x-48\ge0\Rightarrow\left|5x-48\right|=5x-48\)

Ta có phương trình;

\(5x-48=52\)

\(\Leftrightarrow5x=100\)

\(\Leftrightarrow x=20\)(thỏa măn)

  +Trường hợp 2: Nếu\(x< \frac{48}{5}\)thì \(5x-48< 0\Rightarrow\left|5x-48\right|=48-5x\)

Ta có phương trình:

\(48-5x=52\)

\(\Leftrightarrow-5x=4\)

\(\Leftrightarrow x=-\frac{4}{5}\)(thỏa mãn)

\(S=\left\{20;-\frac{4}{5}\right\}\)

Ta có: \(\frac{80}{x+4}+\frac{80}{x-4}=\frac{25}{3}\)

    \(\Leftrightarrow80.\left[\frac{x-4+x+4}{\left(x+4\right).\left(x-4\right)}\right]=\frac{25}{3}\)

    \(\Leftrightarrow\frac{2x}{x^2-16}=\frac{25}{3}:80\)

    \(\Leftrightarrow\frac{2x}{x^2-16}=\frac{5}{48}\)

     \(\Rightarrow48.2x=5.\left(x^2-16\right)\)

    \(\Leftrightarrow96x=5x^2-80\)

    \(\Leftrightarrow5x^2-96x-80=0\)

    \(\Leftrightarrow\left(5x^2-100x\right)+\left(4x-80\right)=0\)

    \(\Leftrightarrow5x.\left(x-20\right)+4.\left(x-20\right)=0\)

    \(\Leftrightarrow\left(5x+4\right).\left(x-20\right)=0\)

    \(\Leftrightarrow\orbr{\begin{cases}5x+4=0\\x-20=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}5x=-4\\x=20\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-\frac{4}{5}\left(TM\right)\\x=20\left(TM\right)\end{cases}}\)

Vậy \(S=\left\{-\frac{4}{5};20\right\}\)

Cách khác , mk cx chwua xm cách trên nhưng mk nghĩ là khác.

ĐKXĐ : \(\hept{\begin{cases}x+4\ne0\\x-4\ne0\end{cases}\Rightarrow\hept{\begin{cases}x\ne-4\\x\ne4\end{cases}}}\)

\(\frac{80}{x+4}+\frac{80}{x-4}=\frac{25}{3}\)

\(\frac{80\left(x-4\right)3}{\left(x+4\right)\left(x-4\right)3}+\frac{80\left(x+4\right)3}{\left(x-4\right)\left(x+4\right)3}=\frac{25\left(x+4\right)\left(x-4\right)}{3\left(x+4\right)\left(x-4\right)}\)

\(80\left(x-4\right)3+80\left(x+4\right)3=25\left(x+4\right)\left(x-4\right)\)

\(240\left(x-4\right)+240\left(x+4\right)=25\left(x+4\right)\left(x-4\right)\)

\(480x=25x^2-400\)

\(480x-25x^2+400=0\)

\(5\left(96x-5x^2+80\right)=0\)

\(\left(5x+4\right)\left(x-20\right)=0\)

\(\orbr{\begin{cases}5x+4=0\\x-20=0\end{cases}\Leftrightarrow\orbr{\begin{cases}5x=-4\\x=20\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-\frac{4}{5}\\x=20\end{cases}}}\)

Theo ĐKXĐ : => x (TM)

a) X x 4 = 80

       X = 80 : 4

       X = 20

b) 3 x X = 90

       X = 90 : 3

       X = 30

a) \(4^x+4^{x+1}=80\)

\(\Rightarrow4^x+4^x.4=80\)

\(\Rightarrow4^x.\left(1+4\right)=80\)

\(\Rightarrow4^x.5=80\)

\(\Rightarrow4^x=16\)

\(\Rightarrow4^x=4^2\)

\(\Rightarrow x=2\)

Vậy x = 2

a, \(x+30\%x+1,5x=2,5\\ < =>x+0,3x+1,5x=2,5\\ < =>\left(1+0,3+1,5\right)x=2,5\\ < =>2,5x=2,5\\ =>x=\dfrac{2,5}{2,5}=1\)

b, \(2\left(3x-4\right)-3\left(x+2\right)=3\\ < =>6x-8-3x-6=3\\ < =>6x-3x=3+8+6\\ < =>3x=17\\ =>x=\dfrac{17}{3}\)

c, \(-110+7x-80=25+2x-80\\ < =>-110-80+80-25=2x-7x\\ < =>-135=-5x\\ =>x=\dfrac{-135}{-5}=27\)

80 : (3.x - 4) = 16

3x - 4 = 80 : 16

3x - 4 = 5

3x = 5 + 4

3x = 9

x = 9 : 3

x = 3

\(80:\left(3x-1\right)=16\)

\(\Rightarrow3x-4=80:16\)

\(\Rightarrow3x-4=5\)

\(\Rightarrow3x=5+4\)

\(\Rightarrow3x=9\)

\(\Rightarrow x=9:3\)

\(\Rightarrow x=3\)

Vậy \(x=3\)

`5 xx 74 xx 2  = 5xx 2 xx 74 = 10xx74 = 740`

`4xx196xx5 = 4xx5xx196 = 20xx196 = 3920`

`(50 + 25)xx4 = 50xx4 + 25xx4 = 200 + 100 = 300`

`125xx(80+8) = 125xx80 + 125xx8 = 10000 + 1000 = 11000`

Ai biết trả lời nhanh giúp mình nha mình đang cần luôn rất rất rất rất gấp.