Question

Tìm x :

x-20     x+40
____ = _____

x-10     x+70
 

Answer 1

\(\frac{x-20}{x-10}=\frac{x+40}{x+70}\)

\(\Rightarrow\) (x - 20)(x + 70) = (x - 10)(x + 40)

\(\Rightarrow\) x² + 70x - 20x - 140 = x² + 40x - 10x - 400

\(\Rightarrow\) x² + 70x - 20x - x² - 40x + 10x = - 400 + 140

\(\Rightarrow\) 20x = 260

\(\Rightarrow\) x = 130

Answer 2

đề như vậy hả bạn?

\(\frac{x-20}{x-10}=\frac{x+40}{x+70}\)

=> \(\left(x-20\right)\left(x+70\right)=\left(x+40\right)\left(x-10\right)\)

=>    \(x^2+70x-20x-1400=x^2-10x+40x-400\)

=>     \(\left(x^2-x^2\right)+\left(70x-20x+10x-40x\right)=-400+1400\)

=>        \(-43x=1000\Rightarrow x=\frac{-1000}{43}\)

Answer 3

pn ơi bạn Nguyễn Lương Bảo Tiên làm sai rui