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已知整式6x-1的值为2,y-1/2的绝对值为2/3,则(5x...

答案1 =7/6答案2=1/6

根据题意得6x-1=2,|y-12|=32,解得x=12,y=-1或2,原式=5x2y+5xy-7x-4x2y-5xy+7x=x2y,①当x=12,y=-1时,原式=-14;②当x=12,y=2时,原式=12.故选C.

依题意得:(5x 2 y+5xy-7x)-(4x 2 y+5xy-7x)=5x 2 y+5xy-7x-4x 2 y-5xy+7x=x 2 y∵6x-1=2,y 2 -y=2,∴x= 1 2 ,y=2或y=-1.∴原式= - 1 4 或 1 2 .故选C.

∵x+y=-1,∴x4+5x3y+x2y+8x2y2+xy2+5xy3+y4,=(x4+2x2y2+y4)+5xy(x2+y2)+xy(x+y)+6x2y2,=(x2+y2)2+5xy[(x+y)2-2xy]+xy(x+y)+6x2y2,=[(x+y)2-2xy]2+5xy(1-2xy)-xy+6x2y2,=(1-2xy)2+5xy-10x2y2-xy+6x2y2,=1-4xy+4x2y2+5xy-10...

y1=x,y2=1/3x+1.交点(3/2,3/2),当x≤3/2时,y1=x y2=1/3x+1,y3=-4/5x+5,(48/19,35/19)当x≥48/19时取最小值y3=-4/5x+5. 当3/2≤x≤48/19时取最小值y2=1/3x+1 所以,y的最大值为x=3/2,时,y=3/2

根据题意得到 设另一个因式为x+by-3 (x+y-2)(x+by-3) =x^2+bxy-3x+xy+by^2-3y-2x-2by+6 =x^2+(b+1)xy+by^2-5x-(3+2b)y+6 所以b+1=a,3+2b=1 所以a=0,b=-1 a+b=-1

由题意得:2x-4=0 y-1/2=0 所以x=2,y=1/2 所以2m+2=8, 10+8=n 即m=3 ,n=18 2m²-n+4=2*3*3 -18+4 =18-18+4 =4 mn=3*18=54 2m²-n+4分之1mn=54/4=27/2

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