Y=2x-3
2х - 3 = 1
2х = 1 + 3
2х = 4
х = 2
x+y=3
xy=-40
x=3-y
(3-y)*y=-40
3y-y²=-40
y²-3y-40=0
y₁,₂=(3±√(9+160))/2=(3±13)/2
y₁=8, y₂=-5
x₁=-5 x₂=8
1)X^2-49=0
(x-7)(x+7)=0
[x1=7;x2=-7;
2)2x^2-x=0
x(2x-1)=0
[x=0;2x=1;
[x=0;x=0.5;
3)x^2-4x-5=0
X^2-5x+x-5=0
x(x-5)+(x-5)=0
(x+1)(x-5)=0
[x1=-1;x2=5;
4)(x-3)(x-1)=12;
x^2-3x-x+3-12=0
X^2-4x-9=0
D=4+9=13;
x1=2+sqrt(13);
x2=2-sqrt(13);
sqrt-квадратный корень.