Question

Tìm x :

 1.X \ 20 = 12 \ 15

2. X \ 4 = 9\ x

Answer 1

\(\frac{x}{20}=\frac{12}{15}\)

Ta có : \(x.15=20.12\)

     \(\Rightarrow x.15=240\)

                 \(x=240:15=16\)

\(\frac{x}{4}=\frac{9}{x}\)

Ta có : \(x.x=4.9\)

\(\Rightarrow x.x=36\)

\(\Rightarrow x=6\)

Answer 2

1. \(\frac{x}{20}=\frac{12}{15}\)\(=>15x=12.20=>15x=240=>x=16\)

2.\(\frac{x}{4}=\frac{9}{x}\)\(=>x^2=9.4=>x^2=36\)\(=>x=\orbr{\begin{cases}6\\-6\end{cases}}\)

Answer 3

Bài 1 :

\(\frac{x}{20}=\frac{12}{15}\)

\(\Rightarrow x\cdot15=20\cdot12\)

\(\Rightarrow x=\frac{20\cdot12}{15}\)

\(\Rightarrow x=16\)

Vậy \(x=16\)

Bài 2 :

\(\frac{x}{4}=\frac{9}{x}\)

\(\Rightarrow x\cdot x=4\cdot9\)

\(\Rightarrow x^2=36\)

\(\Rightarrow x=6\)hoặc \(x=-6\)

Vậy \(x=6\)hoặc \(x=-6\)