x^2-(2b+4)x + b^2 + 4b =0
x^2-2bx-4x+b^2+4b=0
x^2-2bx+b^2 -4(x-b)=0 (x-b)(x+b) - 4(x-b)=0 (x-b)(x+b-4)=0 x1=b x2=4-b
x^2-(2b+4)x + b^2 + 4b =0
x^2-2bx-4x+b^2+4b=0
x^2-2bx+b^2 -4(x-b)=0 (x-b)(x+b) - 4(x-b)=0 (x-b)(x+b-4)=0 x1=b x2=4-b