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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...

依题意得:(5x2y+5xy-7x)-(4x2y+5xy-7x)=5x2y+5xy-7x-4x2y-5xy+7x=x2y∵6x-1=2,y2-y=2,∴x=12,y=2或y=-1.∴原式=?14或12.故选C.

(5x^2y+5xy-7x)-(4x^y+5xy-7x) =5x^2y+5xy-7x-4x^y-5xy+7x =5x^2y-4x^y ∵y²=4, ∴y=2或-2, 当y=2时,x^y=x²=1/4, 原式=5*(1/4)*2-4*(1/4)=5/2-1=3/2 当y=-2时,x^y=4, 原式=5*(1/4)*(-2)-4*4=-5/2-16=-37/2

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

∵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...

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

(x+1)/2=(2-y)/5=(z-3)/4 10x+10=8-4y=5z-15 y=(1-5x/2) y>=0 所以x=0 所以x>=-5/2 又因为x为非负数,即x>=0 所以1/5=>x>=0 而将上述x,z代入w可得: w=x+1 当x=0 时,w=x+1 有最小值:7 当x=1/5时,w=x+1 有最大值:36/5

5x^2y^|m|-(1/4)y^2-3是三次三项式, ∴|m|=1,m=土1, ∴3m^2-2(2m^2+m)+2(2m^2-5m) =3m^2-4m^2-2m+4m^2-10m =3m^2-12m =-9或15.

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