(2x-3)^2=9-2(x-3)(x+3)

4x²-12x+9=9-2(x²-9)
4x²12x+9-9+2x²-18=0
2x²-12x-18=0
x²-6x-9=0
D=36+36=72
x=6+√72  / 2=6+6√2 /2=6(1+√2) /6=1+√2
x=6-√72 /2=1-√2