16x的平方 8x 1=0-搜答案-百度作业网

X1,X2为方程x²+3x+1=0的两根那么x1²+3x1+1=0x1²=-3x1-1x1（-3x1-1）+8x2+20=-3x1²-x1+8x2+20=-3（

X1.X2是方程:X的平方+3X+1=0的两个实数根则：X1²+3X1+1=0X1²=-3X1-1由韦达定理得：X1+X2=-3X1的三次方+8*X2+20=X1*X1²

X1,X2是方程2x的平方+3x-4=0的两个实数根x1+x2=-3/2x1x2=-2x1^2+2x1x2+x^2=9/4x1^2-2x1x2+x^2=9/4-4x1x2(x1-x2)^2=41/4x

x1+x2=-(m+1)x1x2=m²+m-83x1=x2（x1-3）得3(x1+x2)=x1x2即-3(m+1)=m²+m-8m²+4m-5=0得m=1或m=-5当m=

x1带入方程得：x1²+3x1+1=0再同乘上x1得：x1³+3x1²+x1=0所以x1³=-3x1²-x1=-3(-3x1-1)-x1=8x1+3所

x1+x2=5x1x2=31/x1+1/x2=(x1+x2)/(x1x2)=5/3x1²+x2²=(x1+x2)²-2x1x2=19

x1=(-3+√5）/2；x2=(-3-√5)/2若X1=x1,X2=x2,则X1²+8X2+20=(14-6√5）/4-4(3+√5)+20=7/2-12+20-3√5/2-4√5=23/

由韦达定理得：因为a=1,b=-2m,c=m^2+2m+3所以X1+X2=2mX1X2=m^2+2m+3所以X1^2+X2^2=(X1+X2)^2-2X1X2=2m^2-4m-6由△=b^2-4ac=

△=4(k+1)²-4(k²-1)≥0解得:k≥-1根据韦达定理x1+x2=-2(k+1)x1*x2=k²-1x1²+x2²=(x1+x2)²

X1、X2是方程X^2+3X+1=0的两实数根韦达定理得:X1+X2=-3X1X2=1X1^2+3X1+1=0x1^2=-(3x1+1)x1^3+8x2+20=-x1*(3x1+1)+8x2+20=-

x1+x2=4x1x2=1/2原式=(x1+x2)²÷(x1+x2)/x1x2=x1x2(x1+x2)=2

x1后面的符号应该是平方希望对lz有用

负8又1/8

X的平方-3X+1=0的两个实数根是X1,X2X1+X2=3X1X2=1(X1-X2)^2=(X1+X2)^2-4X1X2=3^2-4=5X1-X2=正负根号5

根据题意得x1+x2=5/2x1x2=-3于是1/x²1+1/x²2=(x²1+x²2)/x²1*x²2=[(x1+x2)²-2x

X1的平方+X2的平方的和=（x1+x2)的平方-2*x1x2根据韦大定理x1+x2=9/2,x1x2=6/2=3求得结果为73/4

答案选4=（1+2006X1+X1的平方+2X1）(1+2006X2+X2的平方+2X2)=(0+2X1)(0+2X2)=4x1x2=4

x1,x2是一元二次方程X的平方一6X一7=0的两个根x1+X2=6,x1x2=-7x1^2+x2^2=x1^2+2x1x2+x2^2-2x1x2=(x1+x2)^2-2x1x2=36+14=50

首先解x*2-4x+2=0的解,解出x1=根号2+2,x2=2-根号2然后可算x1+x2=根号2+2+2-根号2=4x1x2=（根号2+2）（2-根号2）=4-2=2问题1：x1分之1加x2分之1=x

x²-x=0x(x-1)=0x1