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-(1/3)(x^2y^2-xy+3)+2【x^2-1/2(xy-2x+y-1)】+3x-1其中x=-4,y=3.先化简,再求值

      发布时间: 2020-09-09

      -1/3(x²y²-xy+3)+2[x²-1/2(xy-2x+y-1)]+3x-1 =-1/3x²y²+1/3xy-1+2x²-xy+2x-y+1+3x-1 =-1/3x²y²+2x²-2/3xy+5x-y-1 把 x=-4代入,错了哒哟呐,2.-(x²y+3xy-4)+3 (x²y-xy+2) =-x^2y-3xy+4+3x^2y-3xy+6 =2x^2y-6xy+10 3. -1/4(2k^3+4k²-28)+1/2(k^3-2k2+4k) =-1/2k^3-k^2+7+1/2k^3-k^2+2k =-2k^2+2k+7 求值:3x²-(2x²+5x-1)-(3x+1)其中x=10 。Y=3 -1/3(X^2y^2-xy+3)+2[X^2-1/2(XY-2X+Y-1)]+3X-1 =-X^2y^2/3+xy/3-1+2X^2-(XY-2X+Y-1)+3X-1 =-X^2y^2/3+xy/3-1+2X^2-XY+2X-Y+1+3X-1 =-X^2y^2/3-2xy/3+2X^2+5X-Y-1 。直线方程的几种表达方式?_百度知道 满意回答 (1)一般式:Ax+By+C=0 (其中A、B不同时为0) (2)点斜式:y-y0=k(x-x0) (3)截距式:x/a+y/b=1 (4)斜截式: Y=KX+B (K≠0) (5)两点式:(y-y0)/(y0-y1)=(x-x0)/(x0-x1) 。由第一式得到y=2x或y=-2x,得 -16/3y²+32-8/3y-20-y-1 =-16/3y²-11/3y+11。-1/3(X^2y^2-xy+3)+2[X^2-1/2(XY-2X+Y-1)]+3X-1,y=3; 2. 2(2a-b)^2-1/2(2a-b)+3(2a-b)^2+2(2a+b)-13。 1. -1/3(x^2y^2xy+3)+2(x^2-1/2(xy-2x+y-1))+3x-1,最后代入数字算错了,-1/3(x^2y^2-xy+3)+2(x^2-1/2(xy-2x+y-1)+3x-1 =-x^2y^2/3+xy/3-1+2x^2-xy+2x-y+1+3x-1 =-x^2y^2/3-2xy/3+2x^2+2x-y-1。其中x=-4,最后代入数应该是-32哦!。其中X=—4,前面化简正确啦,代入第二式可得结果
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