已知a+b=3,ab=-2,求a^2+b^2及(a-b)^2的值

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已知a+b=3,ab=-2,求a^2+b^2及(a-b)^2的值
已知a+b=3,ab=-2,求a^2+b^2及(a-b)^2的值

已知a+b=3,ab=-2,求a^2+b^2及(a-b)^2的值
a²+b²
=(a+b)²-2ab
=3²-2×(-2)
=9+4
=13
(a-b)²
=(a+b)²-4ab
=3²-4×(-2)
=9+8
=17

13和17

a^2+b^2
=(a+b)^2-2ab
=9-2*(-2)
=13
(a-b)^2
=a^2+b^2-2ab
=13+4
=17

a^2+b^2=(a+b)²-2ab=3²+4=13
(a-b)^2=a²+b²-2ab=13+4=17

a²+b²
=(a+b)²-2ab
=3²-2×(-2)
=9+4
=13
(a-b)²
=(a+b)²-4ab
=3²-4×(-2)
=9+8
=17

a^2+b^2
=(a+b)^2-2ab
=9-2*(-2)
=13
(a-b)^2
=a^2+b^2-2ab
=13+4
=17