22:
\(=x^2-10x+25+4y^2+12y+9=\left(x-5\right)^2+\left(2y+3\right)^2\)
24: \(=x^2-10x+25+9y^2-12y+4\)
=(x-5)^2+(3y-2)^2
26:
=4y^2+12y+9+9x^2-12x+4
=(2y+3)^2+(3x-2)^2
28:
=x^2+8x+16+4y^2+4y+1
=(x+4)^2+(2y+1)^2
30: =x^2+8x+16+9y^2-12y+4
=(x+4)^2+(3y-2)^2