[tex] x^{2} +10x+2=0[/tex]
[tex] x^{2} +2*5*x+2=0[/tex]
[tex] x^{2} +2*5*x+ 5^{2} -5^{2}+2=0[/tex]
[tex]x^{2} +2*5*x+ 5^{2}+2= 5^{2}[/tex]
[tex] (x+5)^{2}+2=25 [/tex]
[tex] (x+5)^{2}=23[/tex]
Answer: [tex](x+5)^{2}-23=0[/tex], the value added to both sides is 25