已知x+y=xy=4 求x^2+^2 x^4+x^ - 知识问答

已知x+y=xy=4 求x^2+^2 x^4+x^4 x^8+y^8的值

2个回答

x²+y²
=(x+y)²-2xy
=4²-2×4
=8
x^4+y^4
=(x²+y²)²-2x²y²
=8²-2×4²
=32
x^8+y^8
=(x^4+y^4)²-2x^4y^4
=32²-2×256
=1024-512
=512

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