-1/4(2K³+4K²-28)+(K³-2K²+4K) ; 3x²-(2x²+5x-1)-(3x+1),其中x=10;(xy-3/2y-1/2)-(xy-3/2x+1),其中 x =10/3,y =8/3; 4y²-﹙x²﹢y﹚﹢﹙x²-4y²﹚,其中 x = - 28 ,y =18
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![-1/4(2K³+4K²-28)+(K³-2K²+4K) ; 3x²-(2x²+5x-1)-(3x+1),其中x=10;(xy-3/2y-1/2)-(xy-3/2x+1),其中 x =10/3,y =8/3; 4y²-﹙x²﹢y﹚﹢﹙x²-4y²﹚,其中 x = - 28 ,y =18](/uploads/image/z/3774643-43-3.jpg?t=-1%2F4%282K%26%23179%3B%2B4K%26%23178%3B-28%29%2B%28K%26%23179%3B-2K%26%23178%3B%EF%BC%8B4K%29+%EF%BC%9B+3x%26%23178%3B%EF%BC%8D%282x%26%23178%3B%2B5x%EF%BC%8D1%29%EF%BC%8D%283x%2B1%29%2C%E5%85%B6%E4%B8%ADx%3D10%3B%28xy%EF%BC%8D3%2F2y%EF%BC%8D1%2F2%29%EF%BC%8D%28xy%EF%BC%8D3%2F2x%2B1%29%2C%E5%85%B6%E4%B8%AD+x+%3D10%2F3%2Cy+%3D8%2F3%3B+4y%26%23178%3B%EF%BC%8D%EF%B9%99x%26%23178%3B%EF%B9%A2y%EF%B9%9A%EF%B9%A2%EF%B9%99x%26%23178%3B%EF%BC%8D4y%26%23178%3B%EF%B9%9A%2C%E5%85%B6%E4%B8%AD+x+%3D+-+28+%2Cy+%3D18)
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-1/4(2K³+4K²-28)+(K³-2K²+4K) ; 3x²-(2x²+5x-1)-(3x+1),其中x=10;(xy-3/2y-1/2)-(xy-3/2x+1),其中 x =10/3,y =8/3; 4y²-﹙x²﹢y﹚﹢﹙x²-4y²﹚,其中 x = - 28 ,y =18
-1/4(2K³+4K²-28)+(K³-2K²+4K) ; 3x²-(2x²+5x-1)-(3x+1),其中x=10;
(xy-3/2y-1/2)-(xy-3/2x+1),其中 x =10/3,y =8/3; 4y²-﹙x²﹢y﹚﹢﹙x²-4y²﹚,其中 x = - 28 ,y =18
-1/4(2K³+4K²-28)+(K³-2K²+4K) ; 3x²-(2x²+5x-1)-(3x+1),其中x=10;(xy-3/2y-1/2)-(xy-3/2x+1),其中 x =10/3,y =8/3; 4y²-﹙x²﹢y﹚﹢﹙x²-4y²﹚,其中 x = - 28 ,y =18
先化简,再代值
(1)1/2(K³-6K²+8K+14)
(2)x(x-8) 20
(3)3/2(x-y-1) -1/2
(4)-y -18
1:负二分之三
2:化简:原式=3y - 4y²,
代入:原式=3*18-4*18²=-1242