X^2-3x+13=0
x=(-(-3)+-√(-3)^2-4*1*13)/(2*1)
x=(3+-√9-52)/2
x=(3+-√-43)/2
x не принадлежит реальным числам!
{x+y^2=5
{3x-y=8
y=(3x-8)
x+(3x-8)^2=5
x+9x^2-48x+64-5=0
9x^2-47x+59=0
D=(-47)^2-4×9×59=2209-2124=85
x1=(-(-47)-V85)/2×9=(47-9,22)/18=2.1
x2=(-(-47)+V85)/2×9=(47+9,22)/18=3.12
y1=3×x1-8
y1=3×2.1-8
y1=6.3-8
y1=-1.7
y2=3×x2-8
y2=3×3.12-8
y2=9.36-8
y2=1.36
(2.1;-1.7); (3.12;1.36)
<span>y=(16-16x+4x²)/(1-x</span>)=4(x-2)²/(1-x)
1-x≠0⇒x≠1⇒x∈(-∞;1) U (1;∞)