\(=\left(x^2+10x+25\right)+\left(y^2+2y+1\right)\)
\(=\left(x+5\right)^2+\left(y+1\right)^2\)
x^2 +10x +26 +y^2 +2y=(x^2+10x+25)+(y^2+2y+1)
=(x+5)^2+(y+1)^2
#)Giải :
\(x^2+10x+26+y^2+2y=\left(x^2+10+25\right)+\left(y^2+2y+1\right)=x^2+2.5.x+5^2+y^2+2y+1=\left(x+5\right)^2+\left(y+1\right)^2\)
Làm rõ hơn
\(x^2+10x+26+y^2+2y\)
\(=x^2+10x+25+1+y^2+2y\)
\(=\left(x^2+10x+25\right)+\left(y^2+2y+1\right)\)
\(=\left(x^2+2.5.x+5^2\right)+\left(y^2+2.y.1+1^2\right)\)
\(=\left(x+5\right)^2+\left(y+1\right)^2\)