Question

x/10=y/7 và x.y=280

Answer 1

Đặt : \(\frac{x}{10}=\frac{y}{7}=k\)

\(\Rightarrow\frac{x}{10}=k\)

\(\Rightarrow\frac{y}{7}=k\)

\(\Rightarrow x=10k;y=7k\)

Ta có : \(10k.7k=280\)

\(70k^2=280\)

\(k^2=4\)

\(\Leftrightarrow\orbr{\begin{cases}k=2\\k=-2\end{cases}}\)

TH1 : \(k=2\)

\(\frac{x}{10}=2\Rightarrow x=20\)

\(\frac{y}{7}=2\Rightarrow y=14\)

TH2 : \(k=-2\)

\(\frac{x}{10}=-2\Rightarrow x=-20\)

\(\frac{y}{7}=-2\Rightarrow y=-14\)

Vậy ..........................

Answer 2

\(\frac{x}{10}=\frac{y}{7}=\frac{x.y}{10.7}=\frac{280}{70}=4\)

\(\Rightarrow x=4.10=40\)

\(y=4.7=28\)

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Answer 3

ai giúp k cho