Question

Determinati x e R din proportiile:

3+x   =   1
8           3-x     

Answer 1

Folosim proprietatea fundamentala a proportiei

$\dfrac{3+x}{8}=\dfrac{1}{3-x}\Rightarrow (3-x)(3+x)=8\Rightarrow9-x^2=8\Rightarrow x^2=1$

$\Rightarrow x_{1;2}=\pm1$

Answer 2

(3+x)(3-x)=8×1
9-3x+3x-x²=8
-x²=8-9
-x²=-1
x=√1 (sper sa fie bun) :) succes