ĐKXĐ: \(x\notin\left\{0;-20\right\}\)

\(\left\{{}\begin{matrix}y=20+x\\\dfrac{100}{x}-\dfrac{100}{20+x}=\dfrac{5}{6}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=x+20\\\dfrac{20}{x}-\dfrac{20}{x+20}=\dfrac{1}{6}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=x+20\\\dfrac{20x+400-20x}{x\left(x+20\right)}=\dfrac{1}{6}\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=x+20\\\dfrac{400}{x\left(x+20\right)}=\dfrac{1}{6}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=x+20\\x\left(x+20\right)=2400\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=x+20\\x^2+20x-2400=0\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=x+20\\\left(x+60\right)\left(x-40\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=x+20\\\left[{}\begin{matrix}x+60=0\\x-40=0\end{matrix}\right.\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}y=x+20\\x\in\left\{-60;40\right\}\end{matrix}\right.\)(nhận)

=>\(\left[{}\begin{matrix}\left\{{}\begin{matrix}x=-60\\y=x+20=-60+20=-40\end{matrix}\right.\\\left\{{}\begin{matrix}x=40\\y=x+20=60\end{matrix}\right.\end{matrix}\right.\)

100 + x = 100 + 20

100 + x = 120

x = 120 - 100

x = 20.

100+x=100+20

100+x=120

       x=120-100

       x=20

k mình nha

100+x=100+20

100+x=120

x=120-100=20

cho mik nha bạn

=) đây là bài giải bằng cách lập pt mà nãy bạn đã đăng nè:v mà giải thì ra vô nghiệm á bạn nên mik ko có làm:v

(x-5).3/10=2000+5

(x-5).3/10=2005

x-5=2005:3/10

x-5=2005.10/3

x-5=20050/3

x=20050/3 +5

x=20065/3

\(\left(x-5\right)\)\(.\)\(\frac{30}{100}\)\(=\)\(20\times100+5\)

\(\left(x-5\right)\)\(.\)\(\frac{3}{10}\)\(=\)\(2005\)

\(\left(x-5\right)\)\(=\)\(2005\)\(\div\)\(\frac{3}{10}\)

\(\left(x-5\right)\)\(=\)\(2005\)\(.\)\(\frac{10}{3}\)

\(\left(x-5\right)\)\(=\)\(\frac{20050}{3}\)

\(x=\frac{20055}{3}\)

Hok tốt

20 x 100 = 2000

2000 : 100 = 20

20 x 100 = 2000

2000 : 100 = 20

20 x 100 = 2000

2000 : 100 = 20

mọi người giải thích rõ dùng mình với ạ