已知x=根号3+根号2,y=根号3-根号2,求2x^2-xy-2y^2
人气:346 ℃ 时间:2019-10-31 12:45:28
解答
x=根号3+根号2,
y=根号3-根号2
xy=1, x+y=2√3,x-y=2√2
2x^2-xy-2y^2
=2(x+y)(x-y)-xy
=2*2√3*2√2-1
=8√6-1
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