\(\frac{400}{x}=\frac{100}{x}+\frac{300}{x}+10+\)\(1\)

<=> \(\frac{400-100-300}{x}=11\)

<=> \(\frac{0}{x}=11\)

băng 0 , 100 , 200 ,hoặc 300

B​an ghi ro cach lm ra di

mệt lw k mún ghi

Ta có: \(\left\{{}\begin{matrix}x-y=10\\\dfrac{300}{y}-\dfrac{300}{x}=1\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=10+y\\\dfrac{300}{y}-\dfrac{300}{10+y}=1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=10+y\\\dfrac{300\left(y+10\right)}{y\left(y+10\right)}-\dfrac{300y}{y\left(y+10\right)}=1\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=10+y\\300y+3000-300y=y\left(y+10\right)\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=10+y\\y^2+10y-3000=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=10+y\\y^2+10y+25-3025=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=10+y\\\left(y+5\right)^2=3025\end{matrix}\right.\)

\(\left\{{}\begin{matrix}\left[{}\begin{matrix}x=y+10\\x=y+10\end{matrix}\right.\\\left[{}\begin{matrix}y+5=55\\y+5=-55\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}x=50+10=60\\x=-60+10=-50\end{matrix}\right.\\\left[{}\begin{matrix}y=50\\y=-60\end{matrix}\right.\end{matrix}\right.\)

Vậy: Hệ phương trình có hai cặp nghiệm là (x,y)\(\in\){(-50;-60);(60;50)}

27*10=270

a) 27 x 10 = 270            1977 x 100 = 197700           14 x 1000 = 14000

   86 x 10 = 860              103 x 100 = 10300               452 x 1000 = 452000

   358 x 10 = 3580          72 x 100 = 7200                    300 x 1000 = 300000

b) 80 : 10 = 8             95 x 1000 = 95000

    300 : 10 = 30         66 x 100 = 6600

    2000 : 10 = 200     78 x 10 = 780

b) 200 x 4 = .800.....              300 x 2 = ..600....

200 x 2 = .400.....             300 x 3 = ...900...

400 x 2 = ...800...             500 x 1 = ..500....

100 x 4 = ..400....             100 x 3 = .300.....

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ai giúp mình với

Bài 1:tìm x thuộc Z

a)x.(x-1)=0

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

Vậy: \(x=0;1\)

b)(x-3).(x+4)=0

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

Vậy: \(x=3;-4\)

c)(2x-4).(x+2)=0

\(\Leftrightarrow2\left(x-2\right).\left(x+2\right)=0\)

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

Vậy: \(x=2;-2\)

d)(x+1)^2.(x-2)^2=0

\(\Leftrightarrow\left[\begin{matrix}x+1=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}x=-1\\x=2\end{matrix}\right.\)

Vậy: \(x=-1;2\)

e) x(x+1).(x+2)^2.(x+3)^3=0

\(\Leftrightarrow\left[\begin{matrix}x=0\\x+1=0\\x+2=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}x=0\\x=-1\\x=-2\\x=-3\end{matrix}\right.\)

Vậy: \(x=0;-1;-2;-3\)

f)(x-9)^5.(x-5)^8=0

\(\Leftrightarrow\left[\begin{matrix}x-9=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}x=9\\x=5\end{matrix}\right.\)

Vậy: \(x=9;5\)

g)x(x+100)^10.(x+2000)^20.(x+300)^300=0

\(\Leftrightarrow\left[\begin{matrix}x=0\\x+100=0\\x+200=0\\x+300=0\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}x=0\\x=-100\\x=-200\\x=-300\end{matrix}\right.\)

Vậy: \(x=0;-100;-200;-300\)

h)(x-2)^2=0

\(\Leftrightarrow x-2=0\)

\(\Leftrightarrow x=2\)

Vậy: \(x=2\)

`100/x-100/(x+10)=1/2`
`<=>(100x+1000-100x)/(x^2+10x)=1/2`
`<=>1000/(x^2+10x)=1/2`
`<=>x^2+10x=2000`
`<=>x^2+10x-2000=0`
`Delta'=25+2000=2025`
`<=>x_1=40,x_2=-50`
Vậy `S={40,-50}`

\(\dfrac{100}{x}=\dfrac{1}{2}+\dfrac{100}{x+10}\Rightarrow\dfrac{100}{x}=\dfrac{x+210}{2x+20}\Rightarrow200x+2000=x^2+210x\)

\(x^2+10x-2000=0\Leftrightarrow\left(x+50\right)\left(x-40\right)=0\Rightarrow x=40\)