y²-(x²+6x+9)= y²-(x+3)²= (y-x-3)(y+x+3)
4х = 18 - 7y
4x = 6 - 5y
18 - 7y = 6 - 5y
7y - 5y = 18 - 6
2y = 12
y = 6
4x = 6 - 5•6
4x = 6 - 30
X = - 24 : 4
X = - 6
Ответ ( - 6 ; 6 )
X² +6x -14 =0 ;
x₁ = -3-√23 ;
x₂ =-3 +√23 .
2x₁ +5x₂- x₁*x₂ =2( -3-√23) +5(-3 +√23) -(-14) = -7+3√23.
x₁ = -3+√23 ;
x₂ =-3 -√23 .
2x₁ +5x₂- x₁*x₂ =2(-3 +√23) +5(-3-√23) -(-14) = -7 - 3√23.
ответ : -7<span> ± </span>3√23 .