Resposta :
Observe que:
[tex](\text{a}+\text{b}})^2=\text{a}^2+2\text{ab}+\text{b}^2[/tex]
Desta maneira, temos que:
[tex](\text{a}+5)^2=\text{a}^2+10\text{a}+25[/tex]
Seja [tex]\text{X}=\text{a}^2+(\text{a}+5)^2[/tex]
Logo, podemos afirmar que:
[tex]\text{X}=\text{a}^2+\text{a}^2+10\text{a}+25=2\text{a}^2+10\text{a}+25[/tex]