已知X加45等于62减去XY X等于5那么Y等于几-搜答案-大师作文网

X+Y=5,XY=2,5X+4Y-3X-2Y+XY=2X+2Y+XY=2(X+Y)+XY=2×5+2=12.

由x-1/x=4两边平方得(x-1/x)^2=16即x^2-2+x^(-2)=16得x^2+x^(-2)=18即x的平方加x的负2次方为18

x^2-x-1=0,x^2-x=1.(1)又有x^2=x+1,x^3=x^2+x.(2).-x^3+2x^2+2009=-x^2-x+2x^2+2009[(2)代入]=x^2-x+2009=1+200

已知x二次方减去5x加1等于0解得：x1=(5+根号(21))/2,x2==(5-根号(21))/2而（x^2+1/(x^2)）=(x+1/x)*(x+1/x)-2=(5*(5+根号(21))/(5+

已知xyx+y＝2

∵xyx+y=2∴xy=2（x+y）∴原式=3x−5×2(x+y)+3y−x+3×2(x+y)−y=−7x−7y5x+5y=−75

3x^2+2xy+y^2-6x-6y+9=0(x+y)^2-6(x+y)+9=0(x+y-3)^2=0x+y=3

√x-√(1/x)=2两边平方x-2×√x×√(1/x)+1/x=2²x-2+1/x=4x+1/x=6所以(1+x²)/x=1/x+x²/x=1/x+x=6

∵x^2-3x+1=0显然x不等于0∴x-3+1/x=0∴x+1/x=3∴x^2+1/x^2+2=9∴x^2+1/x^2=7∴原式=1/(x^2+1+1/x^2)=1/(7+1)=1/8

x^2-5x+1=0显然x不是0,两边除以x有x-5+1/x=0也就是x+1/x=5所以x^2+1/(x^2)=(x+1/x)^2-2=23x^4+1/(x^4)=(x^2+1/(x^2))^2-2=

再答：好评

x²+y²-2x-4y+5=0,可化为(x²-2x+1)+(y²-4y+4)=0,即(x-1)²+(y-2)²=0,因此x-1=0,y-2=

所求=3x(x^3-x-1)+4(x^3-x-1)+2003,又x^3-x-1=0,∴所求=2003

3x^3-x=13x^3=x+13x^4=x^2+x9x^4+12x^3-3x^2-7x+2011=3(x^2+x)+4(x+1)-3x^2-7x+2011=3x^2+3x+4x+4-3x^2-7x+

(x+y)²=x²+y²+2xy=49=x²+y²+24∴x²+y²=25(x-y)²=x²+y²-

x+y=7y=7-xxy=x(7-x)=12x=3或4x=3,y=4或x=4,y=3x-y=1或-1

∵xyx+y=-2，yzy+z=43，zxz+x=-43，∴1x+1y=-12，1y+1z=34，1z+1x=-34，∴2（1x+1y+1z）=-12，即1x+1y+1z=-14，则xyzxy+yz+

∵x减一的绝对值是2∴X-1=±2∴X=3或-1∴当X=3时,▎1+X▎-5=4-5=-1,当X=,-1时,▎1+X▎-5=0-5=-5.

x^2-10x+24=x^2-4x-6x+24=(x^2-4x)-(6x-24)=x(x-4)-6(x-4)=(x-6)(x-4)

x-1/x=3(x-1/x)²=3²x²-2+1/x²=9x²+1/x²=11