a: \(x^2+2x+1=x^2+2\cdot x\cdot1+1^2=\left(x+1\right)^2\)
b: \(25x^2+20xy+4y^2\)
\(=\left(5x\right)^2+2\cdot5x\cdot2y+\left(2y\right)^2\)
\(=\left(5x+2y\right)^2\)
c: \(4x^2-12xy+9y^2\)
\(=\left(2x\right)^2-2\cdot2x\cdot3y+\left(3y\right)^2\)
\(=\left(2x-3y\right)^2\)
d: \(\left(2x+3y\right)^2-2\left(2x+3y\right)+1\)
\(=\left(2x+3y\right)^2-2\cdot\left(2x+3y\right)\cdot1+1^2\)
\(=\left(2x+3y-1\right)^2\)
\(x^2+2x+1=\left(x+1\right)^2\)
\(25x^2+20xy+4y^2=\left(5x+2y\right)^2\)
\(4x^2-12xy+9y^2=\left(2x-3y\right)^2\)
\(\left(2x+3y\right)^2-2\left(2x+3y\right)+1=\left(2x+3y-1\right)^2\)
tip nua nek
