Помогите, пожалуйста, с системой уравнений: y=2x+1 x^2-y+y^2-2xy=4x+21

[latex]\left \{ {{y=2x+1} \atop {x^2-y+y^2-2xy=4x+21}} \right. \\ \left \{ {{y=2x+1} \atop {(x-y)^2-y=4x+21}} \right. \\ \left \{ {{y=2x+1} \atop {(x-2x-1)^2-2x-1=4x+21}} \right. \\ (x-2x-1)^2-2x-1=4x+21\\ (1+x)^2=22+6x\\ 1+x^2+2x-6x-22=0\\ x^2-4x-21=0\\ D=16+84=100\\ x_{12}= \left \{ {{(4-10)/2 } \atop (4+10)/2 } \right. = \left \{ {{- 3 } \atop 7} \right. \\ y_{12}= \left \{ {{2(-3 )+1 } \atop 2*7+1 } \right.= \left \{ {{-5 } \atop 15 } \right. [/latex]

x^2-(2x+1)+(2x+1)^2-2x(2x+1)=4x+21 x^2-2x-1+(4x^2+4x+1)-4x^2-2x-4x-21=0 x^2-2x-1+4x^2+4x+1-4x^2-2x-4x-21=0 x^2-4x-21=0 D=b^2-4ac=16+84=100 x1=(4+√10)/2 x2=(4-√10)/2 y1=2*((4+√10)/2)+1=4+√10+1=5+√10 y2=2*((4-√10)/2)+1=4-√10+1=3-√10