化简x 1分之2x-x的平方 1分之2x 4-搜答案-智慧作业帮

x²－4x＋2＝0由韦达定理得：x1＋x2＝4,x1·x2＝2∴(1)x1+x2+3x1x2=4+3*2=10(2)x2/x1+x1/x2=(x2²+x1²)/x1x2=

5x²+x-5=0两根x1,x2,由韦达定理得x1+x2=-1/5x1x2=-5/5=-1x1²+x2²=(x1+x2)²-2x1x2=(-1/5)²

X1＋X2=-B/A=2X1*X2=C/A=1/2求得X1=1+根号2或者X1=1-根号2从而求出X2的值X1/X2+X2/X1=(X1*X1+X2*X2)/(X1X2)=6

原式=[(1-1分之x+5)-(1-1分之x+4))+(1-1分之x+3)-(1-1分之x+2)]*[(x+3)(x+5)]\(x^2+7x+13)=[(1分之x+2)-(1分之x+3)+(1分之x+

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

=2x/x²-(2x-1)/x²=(2x-2x+1)/x²=1/x²

1/x1+1/x2=(x1+x2)/x1x2伟达定理x1+x2=-b/ax1x2=c/a1-2

再答：还是再答：

设x1,x2是方程2x平方+4x-3=0的两个根,则x1+x2=-2x1·x2=-3/2∴x1平方+x2平方=(x1+x2)²-2x1·x2=(-2)²-2×(-3/2)=4+3=

0.5（x+1）的平方

2x平方-5x-1=0X平方-5/2X-1/2=0X平方-5/2X=1/2X平方-5/2X+5/4的平方=1/2+5/4的平方（X-5/4）平方=33/16X-5/4=正负根号33/4X=正负根号33

=x/(x+2)(x-2)-(x-2)/(x+2)(x-2)=[x-(x-2)]/(x+2)(x-2)=2/(x²-4)

(x-5分之x-5-x分之x)\x的平方-25分之2x=2x/(x-5)*(x-5)(x+5)/2x=x+5

4-4x分之9x-9=9(x-1)/4(1-x)=-9/4

x1+x2=-3/2x1x2=-21/x1+1/x2=（x1+x2)/x1x2=(-3/2)/(-2)=3/4x1²+x2²=(x1+x2)²-2x1x2=(-3/2)&

X1+X2=-6/2=-3X1*X2=-3/21/X1+1/X2=(X1+X2)/(X1X2)=-3/(-3/2)=2

x1+x2=4x1x2=-1(x1+x2)^2/(1/x1+1/x2)=(x1+x2)^2*x1x2/(x1+x2)=x1x2*(x1+x2)=-4

原式=[2x(x+1)/(x+1)(x-1)-x(x-1)/(x-1)²]÷x/(x+1)=[2x/(x-1)-x/(x-1)]×(x+1)/x=x/(x-1)×(x+1)/x=(x+1)/

2x²+5x-3=0（2X-1)(X+3)=0所以有X1=1/2X2=-3或者X1=-3X2=1/2则|x1-x2|=3.51/x1²+1/x2²=4+1/9=37/9