已知a+b=-6,ab=7,则a/b+b/a=
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已知a+b=-6,ab=7,则a/b+b/a=
已知a+b=-6,ab=7,则a/b+b/a=
已知a+b=-6,ab=7,则a/b+b/a=
a/b+b/a
=a²/ab+b²/ab
=(a²+b²)/ab
=[(a²+2ab+b²)-2ab]/ab
=[(a+b)²-2ab]/ab
=[(-6)²-2×7]/7
=22/7
答:
a+b=-6,ab=7
所以:
a/b+b/a
=(a^2+b^2)/(ab)
=[(a+b)^2-2ab ]/(ab)
=[(-6)^2-2*7]/7
=36/7-2
=22/7
22/7
ab=7所以a,b都不为0
a/b+b/a (通分)
=(a²+b²)/ab
=[(a+b)²-2ab]/ab 已知a+b=-6,ab=7
=【(-6)²-2×7】/7
=22/7
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