已知x+y=3,xy=-10,求﹙1﹚x^2-xy+y^2;﹙2﹚x-y的绝对值.
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已知x+y=3,xy=-10,求﹙1﹚x^2-xy+y^2;﹙2﹚x-y的绝对值.
已知x+y=3,xy=-10,求﹙1﹚x^2-xy+y^2;﹙2﹚x-y的绝对值.
已知x+y=3,xy=-10,求﹙1﹚x^2-xy+y^2;﹙2﹚x-y的绝对值.
x^2-xy+y^2
=(x+y)²-3xy
=9+30
=39
(x-y)²
=(x+y)²-4xy
=9+40
=49
Ix-yI
=7
x^2-xy+y^2
=(x+y)²-3xy
=9+30
=39
(x-y)²
=(x+y)²-4xy
=9+40
=49
Ix-yI
=7
(1)x²-xy+y²
=(x+y)²-3xy
=9+30
=39
(2)(x-y)²
=(x+y)²-4xy
=9+40
=49
所以丨x-y丨=7