f: \(\Leftrightarrow x^3+4x-4x^2=0\)
\(\Leftrightarrow x\left(x^2-4x+4\right)=0\)
=>x=0 hoặc x=2
g: \(\Leftrightarrow\left(2x+1-x-3\right)\left(2x+1+x+3\right)=0\)
=>(x-2)(3x+4)=0
=>x=2 hoặc x=-4/3
h: \(\Leftrightarrow x^2-6x+9+y^2+6y+9=0\)
\(\Leftrightarrow\left(x-3\right)^2+\left(y+3\right)^2=0\)
=>x=3 hoặc y=-3