a) x/-2=-4/y=2/4
*x/-2=2/4=>4x=(-2)x2=>x=-1
*-4/y=2/4=>(-4)x4=2y=>y=-8
b)2/x=y/-3
=>xy=-6(câu này đề hơi lạ)
c) x+1/2=8/x+1
=>16=(x+1)(x+1)=>x^2+2x+1=16=>(x+1)^2=16=>(x+1)^2=4^2=>x+1=4=>x=3
a) \(\dfrac{x}{-2}=\dfrac{-4}{y}=\dfrac{2}{4}\)
\(\Rightarrow\dfrac{x}{-2}=\dfrac{2}{4}\)
\(\Rightarrow x=\dfrac{-2.2}{4}=-1\)
\(\Rightarrow\dfrac{-4}{y}=\dfrac{2}{4}\)
\(\Rightarrow x=\dfrac{-4.4}{2}=-8\)
b) \(\dfrac{2}{x}=\dfrac{y}{-3}\)
\(\Rightarrow x.y=2.-3\)
\(\Rightarrow x.y=-6\)
\(\Rightarrow x\) và \(y\inƯ\left(-6\right)=\left\{^+_-1;^+_-2;^+_-3;^+_-6\right\}\)
\(\Rightarrow\left(x;y\right)=\left(-6;1\right);\left(1;-6\right);\left(6;-1\right);\left(-1;6\right);\left(-2;3\right);\left(3;-2\right);\left(2;-3\right);\left(-3;2\right)\) c) \(\dfrac{x+1}{2}=\dfrac{8}{x+1}\)
\(\Rightarrow\left(x+1\right).\left(x+1\right)=2.8\)
\(\Rightarrow\left(x+1\right)^2=16\)
\(\Rightarrow\left(x+1\right)^2=4^2\) hoặc \(\left(x+1\right)^2=\left(-4\right)^2\)
\(x+1=4\) hoặc \(x+1=-4\)
\(x=3\) hoặc \(x=-5\)
