解19-120x=7

(x+3)/(x+2)+(x+9)/(x+8)=(x+5)/(x+4)+(x+7)/(x+6)1+(x+5)/(x+2)(x+8)=1+(x+5)/(x+4)(x+6)x=-5再问：第二步那个1是怎么

将x-7/x-9分解成1+2/(x-9)其他分式同理则原方程等价于1/x-9+1/x-5=1/x-6+1/x-81/x-6-1/x-5=1/x-9-1/x-81/(x-5)(x-6)=1/(x-8)(

(x-2)(x+1)(x+4)(x+7)=19(x+2.5-4.5)(x+2.5-1.5)(x+2.5+1.5)(x+2.5+4.5)=19[(x+2.5)^2-4.5^2][(x+2.5)^2-1.

40%X—15=60.4X=21X=52.53X+20X=112解;23X=112X=112/2319-120%X=71.2X=12X=104分之3-5%X=350.05X=2.75X=55

((X-2)(X-4)-(X-3)^2)/(X-3)(X-4)=((X-5)(X-7)-(X-6)^2)/(X-6)(X-7),-1/(X^2-7X+12)=-1/(X^2-13X+42),6X=30

(x-2)(x+1)(x+4)(x+7)=19(x-2)(x+7)(x+1)(x+4)=19(x²+5x-14)(x²+5x+4)=19(x²+5x)²-10(

[1-1/(x-4)]+[1-1/(x-8)]=[1-1/(x-7)]+[1-1/(x-5)]1/(x-4)+1/(x-8)=1/(x-7)+1/(x-5)(x-4+x-8)/(x-4)(x-8)=(

(x^2+7x+5)^2-3x^2-21x=19原方程可化为(x²+7x+5)²-3(x²+7x+5)-4=0所以(x²+7x+5-4)(x²+7x+

(1)19-120％x=71.20x=12x=10(2)3x+20％x=2.1443x+0.2x=2.1443.2x=2.144x=0.67

我给个思路吧（X+2-1/X+2)-(X+3-1/X+3)=（X+6-1/X+6)-(X+7-1/X+7)1-1/(X+2)-1+1/(X+3)=1-1/(X+6)-1+1/(X+7)剩下的就自己解决

只有一个实根.设f(x)=x^3+2x-19为单调增函数.所以只有一个实根.下面来求这个实根由于f(2)=-7f(3)=11所以这个根在（2,3）内.利用二分法求这个解.取x0=5/2f(5/2)=1

/>因为：x-5/x-6+x-8/x-9=x-7/x-8+x-6/x-7,所以：1+1/(x-6)+1+1/(x-9)=1+1/(x-8)+1+1/(x-7)即：1/(x-6）+1/(x-9)=1/(

1.解方程0.6x=2.52X=2.52÷0.6x=4.2x-0.15x=5.10.85x=5.1X=5.1÷0.85x=62.5x+7x=199.5x=19X=19÷9.5x=22.（1）设x小时后

(1)(X+7)/(X+6)+(X+9)/(X+8)=(X+10)/(X+9)+(X+6)/(X+5)这类方程重在运算的技巧性,观察分母7+9=10+6;6+8=5+9所以先移项:(X+7)/(X+6

通分得[（x-8）(x-4)-(x-9)(x-3)]/(x-3)(x-4)=[(x+7)(x+3)-(x+2)(x+8)]/(x+8)(x+3)解得5/(x-3)(x-4)=5/(x+8)(x+3),

(x+8)/(x-3)-(x-9)/(x-4)=(x+7)/(x+8)-(x+2)/(x+3)[（x-8）(x-4)-(x-9)(x-3)]/(x-3)(x-4)=[(x+7)(x+3)-(x+2)(

这道题不用那么复杂.先移项.(x-4)/(x-5)-(x-5)/(x-6)=(x-7)/(x-8)-(x-8)/( x-9)再通分.（x-4)(x-6)/(x-5)(x-6)-(x-5)(x

60%x+25=400.6x=40-250.6x=15x=25x+30%x=521.3x=52x=4019-120%x=719-7=1.2x1.2x=12x=10x-10%x=180.9x=18x=2

x-x/7-(x/12+x/8)-(x/4+x/20+x/5)=500x-x/7-(5/24)x-x/2=500(1/2-5/24)x-x/7=500(7/24)x-x/7=50049x-24x=50