Question

 biết x mũ 2 trừ y mũ 2 =1 ,áp dụng tinh chat day tỉ số bằng nhau tìm x biết\(\frac{x}{5}=\frac{y}{4}\)

Answer 1

\(x^2-y^2=1\)

Ta có : \(\left(\frac{x}{5}\right)^2=\left(\frac{y}{4}\right)^2\)

\(=>\frac{x^2}{25}=\frac{y^2}{16}\)

A/d dãy ............

\(\frac{x^2-y^2}{25-16}=\frac{1}{9}=>\frac{x}{5}=\frac{y}{4}=\frac{1}{3}\)

\(=>\frac{x}{5}=\frac{1}{3}=>x=\frac{5}{3}\)

\(=>\frac{y}{4}=\frac{1}{3}=>x=\frac{4}{3}\)

Answer 2

\(\frac{x}{5}=\frac{y}{4}\)nên \(\frac{x^2}{25}=\frac{y^2}{16}=\frac{x^2-y^2}{25-16}=\frac{1}{9}\)=> \(\frac{x}{5}=\sqrt{\frac{1}{9}};-\sqrt{\frac{1}{9}}=\frac{1}{3};\frac{-1}{3}\)

=> x = \(\frac{1}{3}.5;\frac{-1}{3}.5=\frac{5}{3};\frac{-5}{3}\)