Răspuns :
x/V20 - V320/10 = 3V80/10
V20 = 2V5
V320= 8V5
V80= 4V5
x/2V5 = (3×4V5)/10 + 8V5/10
x/2V5 = (12V5+8V5)/10
x/2V5 = 20V5/10
x/2V5 = 2V5
x= 2V5 ×2V5
x= 4×5
x=20
[tex]\it \dfrac{^{\sqrt{20})}x}{\ \ \ \sqrt{20}}- \dfrac{\sqrt{320}}{10}=\dfrac{3\sqrt{80}}{10} \Rightarrow \dfrac{x\sqrt20}{20}= \dfrac{3\sqrt{16\cdot5}}{10}+ \dfrac{\sqrt{64\cdot5}}{10}|_{\cdot10} \Rightarrow\\ \\ \\ \Rightarrow \dfrac{x\sqrt{20}}{2}=12\sqrt5+8\sqrt5 \Rightarrow \dfrac{x\cdot2\sqrt5}{2}=20\sqrt5 \Rightarrow x\sqrt5=20\sqrt5 \Rightarrow x=20[/tex]