Question

1.Stiind ca 2x+5y supra 5y= 13 supra 10, Calculati x supra y.
2. Stiind ca:
a) a supra 0,2=0,24 supra b, Calculati 1000 ab,
b) x supra y= z supra t, Calculati 11-xt supra yz.

Answer 1

Răspuns:

Explicație pas cu pas:

1)

$\dfrac{2x+5y}{5y} = \dfrac{13}{10} \iff 10(2x+5y)=5y \cdot 13$

$20x+50y = 75y \iff 20x = 65y - 50t \iff 20x = 15y \ \Big|:5$

$4x = 3y \implies \dfrac{x}{y} = \dfrac{3}{4}$

2)a)

$\dfrac{a}{0,2} = \dfrac{0,24}{b} \iff a \cdot b = 0,2 \cdot 0,24$

$1000 \cdot a \cdot b = 1000 \cdot 0,2 \cdot 0,24 = 2 \cdot 24$

$\implies 1000ab = 48$

b)

$\dfrac{x}{y} = \dfrac{z}{t} \iff xt = yz \iff \dfrac{xt}{yz} = 1$

$11 - \dfrac{xt}{yz} = 11 - 1 \implies 11 - \dfrac{xt}{yz} = -10$