2(х+1)^2-(х-3)*(х+3)=7+х^2

2(х+1)^2-(х-3)*(х+3)=7+х^2
2(x^2+1)-(x^2+3x-3x-9)=7+x^2
2x^2+2-x^2-3x+3x+9=7+x^2
x^2+11=7+x^2
x^2-x^2=11-7
x=3