Question

Calculati:

x/y=5/4 si 2x+3y=9,9

Va rog! Dau coroana​

Answer 1

Răspuns:  x = 2,25  si  y = 1,8

Explicație pas cu pas:

• Cerinta:  Sa se afle numerele x si y.

x/y = 5/4 =>   4 x = 5 y ->  produsul mezilor = produsul extremilor

=>    x /5 = y/4 = k ->  coeficient de proportionalitate

=>   x = 5 k   si  y = 4 k

___________________

2 x + 3 y = 9,9

2 × 5 k + 3 × 4 k = 9,9

10 k + 12 k = 9,9

22 k = 9,9

k = (99/10 ) : 22

k = (99/10) × 1/22

k = 99/220    ⇒   k = 0,45

________________________

x = 5 × 0,45  =>    x = 2,25

y = 4 × 0,45  ⇒    y = 1,8

Answer 2

$\frac{x}{y}=\frac{5}{4}=>x=\frac{5y}{4} \\\\inlocuim\\2(\frac{5y}{4} )+3y=9,9\\\\\frac{10y}{4}+3y=9,9\\ \\10y+12y=39,6\\\\22y=39,6\\\\y=1,8\\\\x=2,25$