
已知x=(根号2+1)/(根号2-1),y=(根号3-1)/(根号3+1),求x²-y²的值
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x=(根号2+1)/(根号2-1)
=(√2+1)²/(2-1)
=2+1+2√2
=3+2√2
y=(根号3-1)/(根号3+1)
=﹙√3-1)²/(3-1)
=(3+1-2√3)/2
=2-√3
x²-y²
=(3+2√2)²-(2-√3﹚²
=9+8+12√2-(4+3-4√3)
=10+12√2+4√3
=(√2+1)²/(2-1)
=2+1+2√2
=3+2√2
y=(根号3-1)/(根号3+1)
=﹙√3-1)²/(3-1)
=(3+1-2√3)/2
=2-√3
x²-y²
=(3+2√2)²-(2-√3﹚²
=9+8+12√2-(4+3-4√3)
=10+12√2+4√3
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