当x=2倍根号2时,求根号x²-6x+9×根号x²+6x+9

当x=2倍根号2时,求根号x²-6x+9×根号x²+6x+9
当x=2倍根号2时,求根号x²-6x+9×根号x²+6x+9

当x=2倍根号2时,求根号x²-6x+9×根号x²+6x+9
解
√(x²-6x+9)×√(x²+6x+9)
=√(x-3)²×√(x+3)²
=√[(x-3)(x+3)]²
=√(x²-9)²
=√(8-9)²
=√(-1)²
=1