Respostas

  • Usuário do Brainly
2014-08-15T18:02:25-03:00
 \left \{ {{x-y=2} \atop { x^{2} + y^{2} =34}} \right.

isolar x
x=2-y

subst/

x² + y² =34
(2-y)²+y²=34
4-4y+y²+y²=34

2y² -4y -30=0  ÷por2
y² -2y -15=0
Δ=b²-4ac
Δ=4+60
Δ=64
√Δ=√64= ± 8

x=(-b ± √Δ)/2a

x'= \frac{2+8}{2} = \frac{10}{2}=5

x"= \frac{2-8}{2} =- \frac{6}{2} =-3

como x=2-y
p/ y'=5
x'=2-5
x'=-3

p/ y"=-3
x"=2-(-3)
x"=2+3
x"=5

S={(-3,5);(5,-3)}