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Varga208
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sa se afle x si y ,stiind ca x/y=3/4 si 3x+y=52
sa se afle x si y ,stiind ca x/y=2/5 si 2x+y=81
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Răspuns :

Nico234679ghd

[tex] \frac{x}{y} = \frac{3}{4} \\ 3x + y = 52 \\ \frac{x}{3} = \frac{y}{4} = k \\ x = 3k \\ y = 4k \\ 3 \times 3k + 4k = 52 \\ 9k + 4k = 52 \\ 13k = 52 \\ k = 52 \div 13 \\ k = 4 \\ x = 3 \times 4 = 12 \\ y = 4 \times 4 = 16 \\ [/tex]
[tex] \frac{x}{y } = \frac{2}{5} \\ x + y = 81 \\ \frac{x}{2} = \frac{y}{5} = k \\ x = 2k \\ y = 5k \\ 2 \times 2k + 5k = 81 \\ 4k + 5k = 81 \\ 9k = 81 \\ k = 81 \div 9 \\ k = 9 \\ x = 2 \times 9 = 18 \\ y = 5 \times 9 = 45 \\ [/tex]
Cocirmariadenis

x / y = 3 / 4 ⇒ 4 x = 3 y ⇒ y = 4 x / 3

3 x + y = 52

3 x + 4 x / 3 = 52

9 x + 4 x = 3 × 52

13 x = 156

x = 156 : 13 ⇒ x = 12

y = 52 - 3 × 12 = 52 - 36 == > y = 16

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x / y = 2 / 5 ⇒ 2 y = 5 x ⇒ y = 5 x / 2

2 x + y = 81

2 x + 5 x / 2 = 81

4 x + 5 x = 2 × 81

9 x = 162

x = 162 : 9 ⇒ x = 18

y = ( 5 × 18 ) / 2 == > y = 45

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