已知x-y=9,x*y=5,求(x+y)的二次方的值.快
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已知x-y=9,x*y=5,求(x+y)的二次方的值.快
(x+y)^2
=(x-y)^2+4xy
=81+20
=101
(x+y)的二次方
=x²+2xy+y²
=x²-2xy+y²+4xy
=(x-y)²+4xy
=9²+4×5
=101
已知x-y=9,x*y=5,求(x+y)的二次方的值.快
(x+y)^2
=(x-y)^2+4xy
=81+20
=101
(x+y)的二次方
=x²+2xy+y²
=x²-2xy+y²+4xy
=(x-y)²+4xy
=9²+4×5
=101