①:x-y=2,xy=3.求x²y-xy²=(?) ②:(3x-2)(-3x-2) ③:(x+3)(x-1)-(x-2)²④:(-2a²)²+(-2a)a的4的次方+(-3a的3次方)⑤:x的3次方-2x²y+xy²⑥:m的4次方-16⑦:已知a
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![①:x-y=2,xy=3.求x²y-xy²=(?) ②:(3x-2)(-3x-2) ③:(x+3)(x-1)-(x-2)²④:(-2a²)²+(-2a)a的4的次方+(-3a的3次方)⑤:x的3次方-2x²y+xy²⑥:m的4次方-16⑦:已知a](/uploads/image/z/2994438-30-8.jpg?t=%E2%91%A0%EF%BC%9Ax-y%3D2%2Cxy%3D3.%E6%B1%82x%26%23178%3By-xy%26%23178%3B%3D%28%3F%29+%E2%91%A1%EF%BC%9A%EF%BC%883x-2%EF%BC%89%EF%BC%88-3x-2%EF%BC%89+%E2%91%A2%EF%BC%9A%EF%BC%88x%2B3%EF%BC%89%EF%BC%88x-1%EF%BC%89-%EF%BC%88x-2%EF%BC%89%26%23178%3B%E2%91%A3%EF%BC%9A%EF%BC%88-2a%26%23178%3B%EF%BC%89%26%23178%3B%2B%EF%BC%88-2a%EF%BC%89a%E7%9A%844%E7%9A%84%E6%AC%A1%E6%96%B9%2B%EF%BC%88-3a%E7%9A%843%E6%AC%A1%E6%96%B9%EF%BC%89%E2%91%A4%EF%BC%9Ax%E7%9A%843%E6%AC%A1%E6%96%B9-2x%26%23178%3By%2Bxy%26%23178%3B%E2%91%A5%EF%BC%9Am%E7%9A%844%E6%AC%A1%E6%96%B9-16%E2%91%A6%EF%BC%9A%E5%B7%B2%E7%9F%A5a)
①:x-y=2,xy=3.求x²y-xy²=(?) ②:(3x-2)(-3x-2) ③:(x+3)(x-1)-(x-2)²④:(-2a²)²+(-2a)a的4的次方+(-3a的3次方)⑤:x的3次方-2x²y+xy²⑥:m的4次方-16⑦:已知a
①:x-y=2,xy=3.求x²y-xy²=(?) ②:(3x-2)(-3x-2) ③:(x+3)(x-1)-(x-2)²
④:(-2a²)²+(-2a)a的4的次方+(-3a的3次方)
⑤:x的3次方-2x²y+xy²
⑥:m的4次方-16
⑦:已知a+b=3,ab=-1,求1:a²+b²的值;2:(a-b)²的值
注:
①:x-y=2,xy=3.求x²y-xy²=(?) ②:(3x-2)(-3x-2) ③:(x+3)(x-1)-(x-2)²④:(-2a²)²+(-2a)a的4的次方+(-3a的3次方)⑤:x的3次方-2x²y+xy²⑥:m的4次方-16⑦:已知a
①:x-y=2,xy=3.求x²y-xy²=(?)
x²y-xy²
=xy(x-y)
=3×2
=6
②:(3x-2)(-3x-2)=-9x²+4
③:(x+3)(x-1)-(x-2)²
=x²+2x-3-x²+4x-4
=6x-7
④:(-2a²)²+(-2a)a的4的次方+(-3a的3次方)
=4a的4的次方-2a的5次方-3a的3的次方
⑤:x的3次方-2x²y+xy²
=x(x²-2xy+y²)
=x(x-y)²
⑥:m的4次方-16
=(m²+4)(m²-4)
=(m²+4)(m+2)(m-2)
⑦:已知a+b=3,ab=-1,求1:a²+b²的值;2:(a-b)²的值
a²+b²=(a+b)²-2ab=3²+2=11
(a-b)²=a²+b²-2ab=11+2=13