(x+9)²>2(x-9)(x-1)-(x-1)²
x²+18x+81>2(x²-10x+9)-(x²-2x+1)
x²+18x+81>2x²-20x+18-x²+2x-1
x²-2x²+x²+20x-2x+18x+81-18+1>0
36x+64>0
x>-64/36=-16/9
②
x²+1/x²
=(x+1/x)²-2
=3²-2
=9-2
=7