1/(xy)等于多少1/x 1/y
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/11 09:27:43
![1/(xy)等于多少1/x 1/y](/uploads/image/f/47735-71-5.jpg?t=1%2F%28xy%29%E7%AD%89%E4%BA%8E%E5%A4%9A%E5%B0%911%2Fx+1%2Fy)
X1^2+3X1+1=0----3X1=-1-X1^2X2^2+3X2+1=02x1的二次方+x2的二次方+3x1=2X1^2+X2^2-1-X1^2=X1^2+X2^2-1=[x1+x2]^2-2x
原式=xy(y^4-1)=xy(x²+1)(x²-1)=xy(x²+1)(x+1)(x-1)
(x-y)^2=(x+y)^2-4xy=5^2-4*1=21
4x^2-2x-1=0根据韦达定理:x1+x2=-(-2)/4=1/2
XY=1,x=y所以x^2=1得x=y=1或-1当x=y=1时x^2-3y+1=-1当x=y=-1时x^2-3y+1=5
-5x+2-3xy-5y因为xy=1所以原式=-5x-5y-1-5(x+y)-1因为x+y=3所以-15-1=-16
(1/2xy+y平方+1)+(x平方-1/2xy-2y平方-1)=1/2xy+y²+1+x²-1/2xy-2y²-1=x²-y²
x^2+2xy+y^2=(x^2+xy)+(xy+y^2)=2+7=9再问:不等式4x减3小于2x加5的解集是多少?
X1,X2为方程x的平方+3X+1=0的两实根,x1²+3x1+1=0x2²+3x2+1=0x1x2=1,x1+x2=-3所以X1的平方—3乘X2+20=-3x1-1-3x2+20
(-1/2xy)³=(-1/2)³x³y³=-1/8x³y³
3x²-xy+y²=101-xy+4y²=421-2得3x²-3y²=6x²-y²=2选B
1/x-1/y=3则x-y=-3xyx-3xy-y/2x-xy-2y=(-3xy-3xy)/(-6xy-xy)=6/7
1/x-1/y=2(y-x)/xy=2y-x=2xy(3x+5xy-3y)/(x-xy-y)=[5xy-3(y-x)]/[-xy-(y-x)]=(5xy-6xy)/(-xy-2xy)=-xy/-3xy
解法一-1-x=3^x-1-x=log3xf(x)=3^x与g(x)=log3x互为反函数所以它们的图像关于y=x对称而-1-x的图像也关于y=x对称在坐标系上画出图像可知这两个函数与-1-x的交点关
x1、x2是方程是根,则:(x1)²+3(x1)+1=0,即:(x1)²=-3(x1)-1且x1+x2=-3x1³+8x2+20=x1(-3x1-1)+8x2+20=-3
1÷(¼xy)=4/xy
X1,X2为方程X^2+3X+1=0的两实根x1^2=-1-3x1x1+x2=-3x1*x2=1X1^3+8X2+20=x1(x1^2)+8x2+20=x1(-1-3x1)+8x2+20=-x1-3x
得0=(-X+X)y=0×y=0
若x1>x2,则为x1-x2;若x1=x2,则为0;若x1
当x=(5-根号5)/10时,y=(5+根号5)/10;当x=(5+根号5)/10时,y=(5-根号5)/10查看原帖