Tìm x, biết: (x-20):(x-10)=(x+40):(x+70)
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Tìm x biết:
(x-20)÷(x-10)=(x+40)÷(x+70)
\(\frac{x-20}{x-10}=\frac{x+40}{x+70}\)
\(\Rightarrow\left(x-20\right)\left(x+70\right)=\left(x-10\right)\left(x+40\right)\)
\(\Rightarrow x^2+70x-20x-1400=x^2+40x-10x-400\)
\(\Rightarrow x^2+70x-20x-x^2-40x+10x=1400-400\)
\(\Rightarrow20x=1000\Rightarrow x=50\)
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Tìm x biết:
(x - 20) : ( x + 40)= ( x -10) : ( x +70)
Tìm x, biết:
a) (x+15) : x = 4:3
b) (x-20) : (x-10) = (x+40) : (x+70)
a) (x + 15) : x = 4 : 3
=> x : x + 15 : x = \(\frac{4}{3}\)
=> 1 + 15 : x = \(\frac{4}{3}\)
=> 15 : x = \(\frac{4}{3}\)- 1 = \(\frac{1}{3}\)
=> x = 15 : \(\frac{1}{3}\)
=> x = 45
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phượng quyên là otaku sa( hình đại diện so cute)
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Tìm x biết \(\frac{x-20}{x-10}=\frac{x+40}{x+70}\)
Tìm x (x-20):(x-10)=(x+40):(x+70)
ĐKXĐ: \(\hept{\begin{cases}x\ne10\\x\ne-70\end{cases}}\)
\(\frac{x-20}{x-10}=\frac{x+40}{x+70}\)
\(\Rightarrow\left(x-20\right)\left(x+70\right)=\left(x+40\right)\left(x-10\right)\)
\(\Rightarrow x^2+70x-20x-1400=x^2-10x+40x-400\)
\(\Rightarrow20x=1000\Rightarrow x=50\)
Vậy x = 50
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Tìm x, biết :
a) (x + 15) : x = 4:3
b) (7,5 - x) : (3,5 + x) = 5:6
c) (x - 20) : (x - 10) = (x + 40) : (x + 70)
\(a,\frac{x+15}{x}=\frac{4}{3}\Rightarrow4x=3x+45\Leftrightarrow x=45\)
\(b,\frac{7,5-x}{3,5+x}=\frac{5}{6}\Rightarrow17,5+5x=45-6x\Leftrightarrow11x=27,5\Rightarrow x=2,5\)
\(c,\frac{x-20}{x-10}=\frac{x+40}{x+70}\Rightarrow\left(x-20\right)\left(x+70\right)=\left(x-10\right)\left(x+40\right)\)
\(\Leftrightarrow x^2+50x-1400=x^2+30x-400\)
\(\Leftrightarrow20x=1000\)
\(\Rightarrow x=50\)
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Tìm x biết:
a, (x+15):x =4:3
b, (7,5-x) :(3,5+x)= 5:6
c, (x+20):(x-10)=(x+40):(x+70)
a. \(\frac{\left(x+15\right)}{x}=\frac{4}{3}\Leftrightarrow4x=3\left(x+15\right)\Leftrightarrow4x=3x+45\Leftrightarrow x=45\)
Vậy x=45
b. \(\frac{7,5-x}{3,5+x}=\frac{5}{6}\Leftrightarrow5\left(3,5+x\right)=6\left(7,5-x\right)\Leftrightarrow17,5+5x=45-6x\Leftrightarrow11x=27,5\Leftrightarrow x=2,5\)
Vậy x=2,5
c. \(\frac{x+20}{x-10}=\frac{x+40}{x+70}\Leftrightarrow\left(x+40\right)\left(x-10\right)=\left(x+20\right)\left(x+70\right)\)
\(\Leftrightarrow x^2+30x-400=x^2+90x+1400\Leftrightarrow-60x=-30\Leftrightarrow x=-30\)
Vậy x=-30
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Tìm x biết: \(\frac{x+10}{90}+\frac{x+20}{80}+\frac{x+30}{70}+\frac{x+40}{60}+\frac{x+50}{50}\)
Tìm x biết: \(\frac{x+10}{90}+\frac{x+20}{80}+\frac{x+30}{70}+\frac{x+40}{60}+\frac{x+50}{50}=-5\)
\(\frac{x+10}{90}+\frac{x+20}{80}+\frac{x+30}{70}+\frac{x+40}{60}+\frac{x+50}{50}=-5\)
<=> \(\frac{x+10}{90}+1+\frac{x+20}{80}+1+\frac{x+30}{70}+1+\frac{x+40}{60}+1+\frac{x+50}{50}+1=0\)
<=> \(\frac{x+100}{90}+\frac{x+100}{80}+\frac{x+100}{70}+\frac{x+100}{60}+\frac{x+100}{50}=0\)
<=> \(\left(x+100\right)\left(\frac{1}{90}+\frac{1}{80}+\frac{1}{70}+\frac{1}{60}+\frac{1}{50}\right)=0\)
<=> x + 100 = 0
<=> x = -100
Vậy x = -100