Question

Tìm x trong các tỉ lệ thức sau:

\(\frac{x-1}{x+2}=\frac{x-2}{x+3}\)

Answer 1

\(\dfrac{x-1}{x+2}=\dfrac{x-2}{x+3}\)

\(\Rightarrow x^2-x+3x-3=x^2-4\)

\(\Rightarrow x^2-2x-3=x^2-4\)

\(\Rightarrow-2x-3=-4\)

\(\Rightarrow-2x=-1\)

\(\Rightarrow x=\dfrac{1}{2}\)

Vậy \(x=\dfrac{1}{2}\)

Answer 2

Có:a-b/a=a/a-b/a=1-b/a

Có:c-d/c=c/c-d/c=1-d/c

Mà a/b=c/d nên b/a=d/c suy ra 1-b/a=1-d/c suy ra a-b/a=c-d/c