ab=-1,a+b=2,则式子b/a+a/b=

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ab=-1,a+b=2,则式子b/a+a/b=
ab=-1,a+b=2,则式子b/a+a/b=

ab=-1,a+b=2,则式子b/a+a/b=
b/a+a/b
=(b²+a²)/ab
=[(a+b)²-2ab]/ab
=(a+b)²/ab-2
=2²/(-1)-2
=-4-2
=-6

b/a+a/b
=(b²+a²)/ab
=[(a+b)²-2ab]/ab
因ab=-1,a+b=2 所以有:
原式=[2²-2x(-1)]/(-1)=-6

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解由
b/a+a/b
=b^2/ab+a^2/ab
=(b^2+a^2)/ab
=[(b+a)^2-2ab]/ab
=[(2)^2-2(-1)]/(-1)
=(4+2)/(-1)
=-6