(1)已知x-2y=1/2,xy=2,求多项式-x^4y^2+4x³y³-4x²y^4的值(2)填空:9(x-y)²-(x²-y²)²=____.(3)已知a+b=3,b-a=16,求4a²-4b²的值.(4)计算:(a+2b)²-(3a+b)² (
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![(1)已知x-2y=1/2,xy=2,求多项式-x^4y^2+4x³y³-4x²y^4的值(2)填空:9(x-y)²-(x²-y²)²=____.(3)已知a+b=3,b-a=16,求4a²-4b²的值.(4)计算:(a+2b)²-(3a+b)² (](/uploads/image/z/3003828-60-8.jpg?t=%EF%BC%881%EF%BC%89%E5%B7%B2%E7%9F%A5x-2y%3D1%2F2%2Cxy%3D2%2C%E6%B1%82%E5%A4%9A%E9%A1%B9%E5%BC%8F-x%5E4y%5E2%2B4x%26%23179%3By%26%23179%3B-4x%26%23178%3By%5E4%E7%9A%84%E5%80%BC%EF%BC%882%EF%BC%89%E5%A1%AB%E7%A9%BA%EF%BC%9A9%EF%BC%88x-y%EF%BC%89%26%23178%3B-%EF%BC%88x%26%23178%3B-y%26%23178%3B%EF%BC%89%26%23178%3B%3D____.%EF%BC%883%EF%BC%89%E5%B7%B2%E7%9F%A5a%2Bb%3D3%2Cb-a%3D16%2C%E6%B1%824a%26%23178%3B-4b%26%23178%3B%E7%9A%84%E5%80%BC.%EF%BC%884%EF%BC%89%E8%AE%A1%E7%AE%97%EF%BC%9A%EF%BC%88a%2B2b%29%26%23178%3B-%EF%BC%883a%2Bb%EF%BC%89%26%23178%3B+%EF%BC%88)
(1)已知x-2y=1/2,xy=2,求多项式-x^4y^2+4x³y³-4x²y^4的值(2)填空:9(x-y)²-(x²-y²)²=____.(3)已知a+b=3,b-a=16,求4a²-4b²的值.(4)计算:(a+2b)²-(3a+b)² (
(1)已知x-2y=1/2,xy=2,求多项式-x^4y^2+4x³y³-4x²y^4的值
(2)填空:9(x-y)²-(x²-y²)²=____.(3)已知a+b=3,b-a=16,求4a²-4b²的值.(4)计算:(a+2b)²-(3a+b)² (x+y)²-8(x²-y²)+16(x-y)²
(1)已知x-2y=1/2,xy=2,求多项式-x^4y^2+4x³y³-4x²y^4的值(2)填空:9(x-y)²-(x²-y²)²=____.(3)已知a+b=3,b-a=16,求4a²-4b²的值.(4)计算:(a+2b)²-(3a+b)² (
(1)已知x-2y=1/2,xy=2,求多项式-x^4y^2+4x³y³-4x²y^4的值
-x^4y^2+4x³y³-4x²y^4
=-x²y²(x²-4xy+4y²)
=-(xy)²(x-2y)²
=-(1/2)²*2²
=-1
(2)填空:9(x-y)²-(x²-y²)²=(x-y)²(3-x-y)(3+x+y)
(3)已知a+b=3,b-a=16,求4a²-4b²的值.
4a²-4b²
=4(a+b)(a-b)
=4×3×(-16)
=-192
(4)计算:
(a+2b)²-(3a+b)²
=(a+2b-3a-b)(a+2b+3a+b)
=(-2a+b)(4a+3b)
=-8a²-2ab+3b²
(x+y)²-8(x²-y²)+16(x-y)²
=(x+y-4x+4y)²
=(-3x+5y)²
=9x²-30xy+25y²