Question

постройте график уравнения
( y+2x)•(y-x-1)=0

Answer 1

$(y+2x)cdot(y-x-1)=0, \ y^2-xy-y+2xy-2x^2-2x = 0, \ y^2+xy-y-2x^2-2x=0, \ y^2+y(x-1)-2x^2-2x=0, \ D=(x-1)^2-4(-2x^2-2x)=x^2-2x+1+8x^2+8x=\=9x^2+6x+1=(3x+1)^2, \ y=frac{1}{2}(-(x-1)pmsqrt{(3x+1)^2})=frac{1}{2}(1-xpm|3x+1|), \ y= left [ {{x+1,} atop {-2x.}} right.$