[tex]|AB|=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2} \\\sqrt{5} =\sqrt{(x-1)^2+((7+x)-7)^2} |^2\\5=(x-1)^2+((7+x)-7)^2\\5=x^2-2x+1+x^2\\5=2x^2-2x+1\\5-2x^2+2x-1=0\\-2x^2+2x+5-1=0\\-2x^2+2x+4=0 |:(-2)\\x^2-x-2=0\\\Delta=(-1)^2-4\cdot1\cdot(-2)=1-(-8)=1+8=9\\\sqrt{\Delta} =\sqrt{9} =3\\\boxed{x_1=\frac{1-3}{2\cdot1} =\frac{-2}{2} =-1}\\ \boxed{x_2=\frac{1+3}{2\cdot1} =\frac{4}{2} =2}[/tex]