已知x+y=2,xy=1⼀2求x的三次方y-2x的二次方y的二次方+xy的三次方旳值

2025-03-01 20:18:15
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回答1:

x+y=2,xy=1/2

x的三次方y-2x的二次方y的二次方+xy的三次方
=xy(x²-2xy+y²)

=1/2(x²+2xy+y²-4xy)
=1/2[(x+y)²-4×1/2]
=1/2(4-2)
=1