Х=2-у подставим во второе уравнение
2-у-у=3
-2у=1
у=-1/2= -0.5
х=2-(-0.5)=2+0.5=2.5
Ответ(2.5 ;-0.5)
дискриминант=(-1) в квадрате-4*1*(-72)=1+288=289
дискриминант=17
ф-ла корней
1) (x + 1)³ + (x - 1)³ 2x³ = 12; (x+ 1 + x - 1)((x + 1)² - (x + 1)(x - 1) + (x - 1)² - 2x³ =12; 2x(x² + 2x + 1 - x² + 1 + x² - 2x + 1 - 2x³ = 12; 2x(x² + 3) - 2x³ =12; 2x(x² + 3 - x²) =12; 6x = 12; x = 2; 2) (1 + y)³ + (1 - y)³ -6y² = 3y - 1; (1 + y + 1 - y)((1 + y)² - (1 + y)(1 - y) + (1 - y)²) - 6y² = 3y - 1; 2(1 + 2y + 1 - 1 + y² + 1 - 2y + y²) - 6y² = 3y - 1; 4 + 4y² - 6y² - 3y + 1 = 0; 2y² + 3y - 5 = 0; D = 49; x₁ = 1; x₂ = - 2,5
Y = <span>1+12х-9х²;
y '(x) = 12 - 18 x;
y'= 0;
12 - 18 x = 0;
- 18x = -12;
x = 12/18 = 2/3;
y(2/3) = 1 + 12/1 * 2/3 - 9/1 * (4/9) = 1 + 8 - 4 = 5</span>