X(x^2-11x+28) = 0
X=0 x^2-11x+28 =0
D = 121 - 112 = 9= 3^2
X1 = 7 X2=4
<span>x^3+7x^2-18x = 0
x(x^2 +7x - 18) = 0
x=0 x^2+7x-18 = 0
D = 49 +72 = 121 = 11^2
x1 = 2 X2 = -9
</span>
<span>5x^4-6x^3+x^2=0
X^2(5x^2 - 6x + 1) =0
x^2 =0 5x^2 - 6x +1 =0
x = 0 D = 36 -20 = 16 = 4^2
x1 = 1 x2=0.2
</span>
16а∧6-8а³b+b²..........................
2xy=12
x² + y² = 13
Складывая и вычитая получаем новую систему
x² + 2xy + y² =25
x² - 2xy + y² = 1
x+y=5
x-y=1 x=3 y=2
или
x + y =5
x-y = -1 x=2 y=3
x+y =-5
x-y = 1 x=-2 y=-3
x+y = -5
x-y =-1 x=-3 y=-2
.........................