Tìm số nguyên x,y sao cho \(\dfrac{-4}{11}\)=\(\dfrac{X}{22}\)=\(\dfrac{40}{Y}\)
giúp mik vớiii
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\(\Rightarrow3xy=12-11y\Leftrightarrow3xy+11y=12\)
\(\Leftrightarrow y\left(3x+11\right)=12\Rightarrow y;3x+11\inƯ\left(12\right)=12\left\{\pm1;\pm2;\pm3;\pm4;\pm6;\pm\right\}\)
-> bạn tự lập bảng
\(a,\dfrac{x}{5}=-\dfrac{3}{y}\Rightarrow xy=-15\\ \Rightarrow xy=-1\cdot15=-15\cdot1=-5\cdot3=-3\cdot5\\ \Rightarrow\left(x;y\right)=\left\{\left(-1;-15\right);\left(1;-15\right);\left(15;-1\right);\left(-15;1\right);\left(3;-5\right);\left(-5;3\right);\left(5;-3\right);\left(-3;5\right)\right\}\)\(g,-\dfrac{11}{x}=\dfrac{y}{3}\\ \Rightarrow xy=-33\\ \Rightarrow xy=-3\cdot11=-11\cdot3=-1\cdot33=-33\cdot1\\ \Rightarrow\left(x;y\right)=\left\{\left(-3;11\right);\left(11;-3\right);\left(-11;3\right);\left(3;-11\right);\left(-1;33\right);\left(33;-1\right);\left(-33;1\right);\left(1;-33\right)\right\}\)
a: =>-2x=90/91
hay x=-45/91
b: =>2x=-7
hay x=-7/2
c: ->-3x=-12
hay x=4
a) Áp dụng t/c dtsbn:
\(\dfrac{x}{7}=\dfrac{y}{13}=\dfrac{x+y}{7+13}=\dfrac{40}{20}=2\)
\(\Rightarrow\left\{{}\begin{matrix}x=2.7=14\\y=2.13=26\end{matrix}\right.\)
b) \(\dfrac{3}{x}=\dfrac{7}{y}\Rightarrow\dfrac{x}{3}=\dfrac{y}{7}\)
Và \(x+16=y\Rightarrow y-x=16\)
Áp dụng t/c dtsbn:
\(\dfrac{x}{3}=\dfrac{y}{7}=\dfrac{y-x}{7-3}=\dfrac{16}{4}=4\)
\(\Rightarrow\left\{{}\begin{matrix}x=4.3=12\\y=4.7=28\end{matrix}\right.\)
Áp dụng tính chất của dãy tỉ số bằng nhau, ta có:
\(\begin{array}{l}\dfrac{x}{9} = \dfrac{y}{{11}} = \dfrac{{x + y}}{{9 + 11}} = \dfrac{{40}}{{20}} = 2\\ \Rightarrow x = 2.9 = 18\\y = 2.11 = 22\end{array}\)
Vậy x= 18, y = 22.
\(\dfrac{-4}{11}\) = \(\dfrac{x}{22}\) = \(\dfrac{40}{y}\)
\(x\) = -\(\dfrac{4}{11}\).22 = -8
y = 40 :( -\(\dfrac{4}{11}\))
y = - 110
Vậy (\(x\);y) =(-8; -110)
\(\dfrac{-4}{11}=\dfrac{x}{22}=\dfrac{40}{y}\)
\(\Rightarrow\dfrac{-4}{11}=\dfrac{x}{22}\)
\(\Rightarrow\dfrac{-4}{11}=\dfrac{-4\cdot2}{11\cdot2}=\dfrac{-8}{22}\)
\(\Rightarrow\dfrac{-8}{22}=\dfrac{40}{y}\)
\(\Rightarrow\dfrac{-8}{22}=\dfrac{-8\cdot\left(-5\right)}{22\cdot\left(-5\right)}=\dfrac{40}{-110}\)
\(\Rightarrow\dfrac{-4}{11}=\dfrac{-8}{22}=\dfrac{40}{-110}\)
\(\Rightarrow\left(x,y\right)=\left(-8;-110\right)\)