Question

Cum resolv C15? Mersi :)

Answer 1

Răspuns:

x = 1 ; y = 3  si  x = 3 ; y = 1

Explicație pas cu pas:

x+y = 4   => x = 4-y

xy = 3

(4-y)·y = 3 <=>

4y - y² = 3 <=>

4y - y² - 3 = 0  <=>

- y²+4y-3 = 0  I ·(-1)  =>

y²-4y+3 = 0 <=>

y² - 3y - y +3 = 0 <=>

y(y-3)-(y-3) = 0 <=>

(y-3)·(y-1) = 0 => y₁ = 3 ; y₂ = 1

y₁ = 3 => x = 4-3 => x = 1

y₂ = 1 => x = 4-1 => x = 3

Answer 2

Răspuns:

x=3,y=1

y=3,x=1

Explicație pas cu pas:

x+y=4

xy=3

y=4-x

x(4-x)=3

$4x - {x}^{2} = 3$

${x}^{2} - 4 x+ 3 = 0$

${x}^{2} - 3x - x + 3 = 0$

$x(x - 3)( x - 3) = 0$

x-3=0=>x=3

$x \times y = 3 \\ 3 \times y = 3 \\ y = 1$