Question

tìm x,y,z:

x/4 = 3y/9 ; x/2 = 2z/10 và x + 3y - 2z = 36

Answer 1

  \(\dfrac{x}{4}\) = \(\dfrac{3y}{9}\) ; \(\dfrac{x}{2}\) = \(\dfrac{2z}{10}\) ⇒ \(\dfrac{x}{4}\) = \(\dfrac{2z}{20}\) 

⇒ \(\dfrac{x}{4}\) = \(\dfrac{3y}{9}\) = \(\dfrac{2z}{20}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có:

\(\dfrac{x}{4}\) = \(\dfrac{3y}{9}\) = \(\dfrac{2z}{20}\) = \(\dfrac{x+3y-2z}{4+9-20}\) = \(\dfrac{36}{-7}\)

\(x\) = - \(\dfrac{144}{7}\)

y = - \(\dfrac{144}{7}\) : 4 \(\times\) \(\dfrac{9}{3}\) = - \(\dfrac{432}{28}\)

z = - \(\dfrac{144}{7}\) : 2 \(\times\) \(\dfrac{10}{2}\) = - \(\dfrac{720}{14}\)