|3x+2|=5,
3x+2=5 или 3x+2=-5,
3x=3, 3x=-7,
x1=1, x2=-2⅓,
http://webmath.exponenta.ru/s/c/algebra/content/chapter3/section1/paragraph8/theory.html
|x-2|<5,4,
x-2<5,4, x<7,4;
или -(x-2)<5,4, x-2>-5,4, x>-3,4,
-3,4<x<7,4;
x∈(-3,4;7,4)
{|x-2|<5,4, -5,4<x-2<5,4, -3,4<x<7,4}
|3x+2|>5,
3x+2>5, 3x>3, x>1,
или -(3x+2)>5, 3x+2<-5, 3x<-7, x<-2⅓,
x∈(-∞,-2⅓)U(1,+∞)
http://webmath.exponenta.ru/s/c/algebra/content/chapter3/section2/paragraph4/theory.html
{ 3x^2 - 2xy - y^2 = 7 |*2
{ x^2 + xy + 8y^2 = 14
6x^2 - 4xy - 2y^2 = 14
6x^2 - 4xy - 2y^2= x^2 + xy + 8y^2
5x^2 - 5xy - 10y^2= 0
x^2 - xy - 2y^2= 0
D = y^2 + 8y^2 = 9y^2
x12 = (y +- 3y)/2= -y 2y
(x + y)(x - 2y) = 0
1 . x = -y
y^2 - y^2 + 8y^2 = 14
y^2 = 7/4
y1 = √7/2 x1 = -√7/2
y2 = -√7/2 x2 = √7/2
2. x = 2y
4y^2 + 2y^2 + 8y^2 = 14
y^2 = 1
y3 = 1 x3 = 2
y4 = -1 x4=-2