已知x+y=2.xy=½.求1.½x²+½y²;2.x³y+2x²y²+xy³的值
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![已知x+y=2.xy=½.求1.½x²+½y²;2.x³y+2x²y²+xy³的值](/uploads/image/z/4326911-71-1.jpg?t=%E5%B7%B2%E7%9F%A5x%2By%3D2.xy%3D%26%23189%3B.%E6%B1%821.%26%23189%3Bx%26%23178%3B%2B%26%23189%3By%26%23178%3B%3B2.x%26%23179%3By%2B2x%26%23178%3By%26%23178%3B%2Bxy%26%23179%3B%E7%9A%84%E5%80%BC)
已知x+y=2.xy=½.求1.½x²+½y²;2.x³y+2x²y²+xy³的值
已知x+y=2.xy=½.求1.½x²+½y²;2.x³y+2x²y²+xy³的值
已知x+y=2.xy=½.求1.½x²+½y²;2.x³y+2x²y²+xy³的值
1.½x²+½y²
=1/2(x+y)²-xy
=1/2*2²-1/2
=3/2
2.x³y+2x²y²+xy³
=xy(x²+2xy+y²)
=xy(x+y)²
=1/2*2
=1