已知x+y=根号3+根号2,xy=根号6,求|x-y|的值

问题描述:

已知x+y=根号3+根号2,xy=根号6,求|x-y|的值


/x-y/
=√(x-y)²
=√(x+y)²-4xy
=√(√3+√2)²-4√6
=√(3+2+2√6-4√6)
=√(3+2-2√6)
=√(√3-√2)²
=√3-√2

|x-y|=根号(x-y)^2=(x+y)^2-4xy=(根号3+根号2)^2-4根号6=5-2根号6 不知计算有没错思路就这样

( ︳X-Y ︳)²=X²+Y²-2XY=X²+Y²+2XY-4XY=(X+Y)²-2XY=3+2-2倍根号6
故 X=根号2,Y=跟号3,或X=根号3,Y=跟号2 又 ︳X-Y︳>0
所以 ︳X-Y︳=跟号3 - 跟号2

x+y=根号3+根号2,xy=根号6
(x+y)^2=5+2根号6,4xy=4根号6
(x-y)^2=5-2根号6=(根号3-根号2)^2
|x-y|=根号3-根号2

(x+y)²=(√3+√2)²x²+2xy+y²=5+2√6x²-2xy+4xy+y²=5+2√6(x-y)²+4×√6=5+2√6(x-y)²=5-2√6(x-y)²=(√3-√2)²|x-y|=√3-√2