x-1分之x 1减x²-1分之4=1-搜答案-搜狗做题网

x-4/9x=1/185/9x=1/18x=1/18x9/5x=1/10

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=

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=（-8）*（-81/20）*5/4*1/10=（-8）*5/4*（-81/20）*1/10=（-10）*1/10*（-81/20）=81/20

12分之5x减4分之x=3分之1x(5/12-1/4)=1/3x(2/12)=1/3x=1/3*6=2

兄弟,真的很简单,但是没有时间给你做你看下韦达定理,全部是基本应用,及两根之和、两根之积的关系,一下就出了.比如第一题,直接通分,第一空-5,第二个-3,第三个是（x1-x2)²=（x1+x

0.75分之x=4分之1

x/0.75=1/4x=1/4÷0.75x=0.25÷0.75x=1/3

x+2分之2x减2=x-2分之1加4-x分之x+14左右两边同×（x+2）(x-2)(4-x)得：（2x-2）(x-2)(4-x)=(x+2)(4-x)+(x+14)(x+2)(x-2)2(x-2)&

=[(x+2)/x(x-2)-(x-1)/(x-2)²]×x/(4-x)=[(x²-4-x²+4)/x(x-2)²]×x/(4-x)=1/(x-2)²

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

x/4+0.75x=1/82x+0.75=12x=0.25x=0.1254（x+0.2）=1.24x=1.2-0.84x=0.4x=0.15x-1/3=2/315x-1=215x=3x=0.2可以重新

利用比例的基本性质1/4=0.75/x1*x=4*0.75x=3

x/(x-2)=(x-4)/(x-5)方程两边同乘(x-2)(x-5),得:x(x-5)=(x-4)(x-2)x^2-5x=x^2-6x+8x=8x/(x-3)=(x+1)/(x-1)x^2-x=x^

（x²-1）/x=3/2x²-1-3/2x=02x²-3x-2=0十字相乘x=-1/2或者x=2

2√2－2或－2√2－2

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

解第一道题两边乘以12得：4(2x-1)-2(10x+1)=3(2x+1)-128x-4-20x-2=6x+3-12-12x-6=6x-96x+12x=9-618x=3x=1/6追问一下再问：谢谢，那

原式=[（x+2）/x（x-2）-（x-1）/（x-2）²]÷（4-x）/x=[（x+2）（x-2）/x（x-2）²-x（x-1）/x（x-2）²]÷（4-x）/x=[（

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

X=4原式=(X-1)/(X-2)-(X-2)/(X-3)=(X-4)/(X-5)-(X-5)/(X-6)左边通分=[X^2-4X+3-X^2+4X-4]/[(X-2)(X-3)]=-1/[(X-2)