求代数式x² y² 2x-6y 21的最小值-搜答案-拍题作业网

你说的是根号X-2+绝对值2Y+6=0吧,由于根号X-2,绝对值2Y+6》0,所以X=2,Y=-3所以立方根X+Y=-1

2x²+3y+7=82x²+3y=1两边乘36x²+9y=36x²+9y+8=3+8=11

原式=1/2×2x-y/x+y+2x-y/6x-3y=1/2+1/3=5/6

(2x-y)/(x+y)=3所以(x+y)/(2x-y)=1/3原式=1/2*(2x-y)/(x+y)+1/3*(x+y)/(2x-y)=3/2+1/9=29/18

已知代数式x²-2y的值为5,求代数式3x²-6y+2的值=3(x²-2y)+2=3×5+2=15+2=17;很高兴为您解答,skyhunter002为您答疑解惑如果本题

9x^2+y^2+6x-4y+7=9x^2+6x+1+y^2-4y+4+2=(3x+1)²+(y-2)²+2≥2所以代数式9x^2+y^2+6x-4y+7的最小值是2

解由x^2-2y=3故3x^2-1-6y=3x^2-6y-1=3(x^2-2y)-1=3×3-1=8

X+Y分之X-Y等于3x=-2yX+Y分之2(x-y)减X+Y分之3X+Y=(-x-3y)/(x+y)=1

因为(x-y)/(x+y)=3,则(x＋y)/(x－y)＝1/3则5(x-y)(x+y)-(x+y)/2(x-y)＝5*3-1/(3*2)=15-1/6=89/6

/>x^2+2x+y^2-6y+10=0可化为(x+1)²+(y-3)²=0∴x=-1,y=3∴x²+y²-xy=1+9+3=13

（x+1）^2+(y-3)^2=0x=-1,y=32x-y=-5

这个题目是这个公式的逆向运用（a+b）^2=a^2+2*a*b+b^2所以我们需要把他给的式子用上面的公式逆向收拢,于是就有：2x^2-8x+8+3y^2+6y+3-8-3+1=2(x-2)^2+3(

(x+y+z)²+(x-y-z)(x-y+z)-2·z(x+y)=(x+y)²+2z(x+y)+z²+(x-y)²-z²-2z(x+y)=(x+y)&

x平方+8x+16+y平方+6x+9=0(x+4)平方+(y+3)平方=0∴x+4=0y+3=0∴x=-4,y=-3原式=(x+2y)(x-2y)/(x+2y)平方-x/(x+2y)=(x-2y)/(

进行公式变化后：(x-1)2+(y+3)2+2003因为平方最小只能是0,所以这个的最小值就是2003.望采纳!

2x-y\x+y=32x-y=3(x+y)2x-y=3x+3y3x-2x=-y-3yx=-4y2x-y/2x+2y+x+y/6x-3y=(-8y-y)/(-8y+2y)+(-4y+y)/(-24y-3

3x2-6y+2=3（x2-2y）+2=3×5+2=17

2x-y=-64x-2y=2(2x-y)=-124x-2y+1=-12+1=-11y-2x=-(2x-y)=-(-6)=66的三次方=216

(3x+y-6)/(4x-y-8)=[3x+y-3(x-2y)]/[4x-y-4(x-2y)]=5y/7y=5/57

原式化简=x＋2y=2011