標題:
中小數學題 20分 急
發問:
1. 3/x=2/x-12. a/a-5 = 3+ 5/a-53. 2/3t + 1/t =5/94. a= 3a-50/4a-24 -3/45. 4/x+2 - 3/x+3 = 6/x^2 +5x+66. 3/x+1 - x-2/2 = x-2/x+17. Solve for y: 1/x=1/y+1/z8. 4/a+2 - 7/a^2 +4a+49. s+7/s+3 - s-3/s+710. 4/s^2 +5s+4 + s/s^2 +2s+111. 2/a^2 +4a+3 + 1/a+312. 9y/x-4 +y13. 7/a-4 + 5/4-a14. c/7c-d... 顯示更多 1. 3/x=2/x-1 2. a/a-5 = 3+ 5/a-5 3. 2/3t + 1/t =5/9 4. a= 3a-50/4a-24 -3/4 5. 4/x+2 - 3/x+3 = 6/x^2 +5x+6 6. 3/x+1 - x-2/2 = x-2/x+1 7. Solve for y: 1/x=1/y+1/z 8. 4/a+2 - 7/a^2 +4a+4 9. s+7/s+3 - s-3/s+7 10. 4/s^2 +5s+4 + s/s^2 +2s+1 11. 2/a^2 +4a+3 + 1/a+3 12. 9y/x-4 +y 13. 7/a-4 + 5/4-a 14. c/7c-d - d/d-7c 15) [1/y-5/2] / [4/x+2 ] 16) [2/3+1] / [1/3+1] 17) [2/x +2] / [4/x +2] 18) [1/6 -2/x] / [1/6+1/x] 19) [d^2/4 + 4d/5] / (d+1)/2 20) [(1/x+1) / 1+ (1/x+1) 21) [x/x+2] / x/x+2 +x
最佳解答:
Errr... I don't know if there is brackets in the question so I will do both. 1. 3/x=2/x-1 3/x=2/(x-1) 3=2-x 3(x-1)=2x -x=1 3x-3=2x x=-1 x=3 2.a/(a-5)=3+5/(a-5) a/(a-5)=(3+5)/(a-5) a/(a-5)=(5+3(a-5))/(a-5) a=3+5 a=5+3a-15 =8 -2a=-10 a=5 3.2/(3t)+1/t=5/9 2/3+1=5t/9 5/3=5t/9 t=3 4.a=(3a-50)/(4a-24)-3/4 a=(3a-50)/(4(a-6))-(3(a-6))/(4(a-6)) a=(3a-50-3a+18)/(4(a-6)) a=32/(4(a-6) a=8/(a-6) a^2-6a-8=0 a=4 or 2 5.4/(x+2)-3/(x+3)=6/(x^2+5x+6) 4/(x+2)-3/(x+3)=6/((x+2)(x+3)) 4(x+3)-3(x+2)=6 x=0 6.3/(x+1)-(x-2)/2=(x-2)/(x+1) 3-(x-2)(x+1)/2=x-2 6-(x^2-x-2)=2x-4 -x^2-x+12=0 x^2+x-12=0 x= 3 or -4 7. 1/x=1/y+1/z y/x-y/z=1 yz-xy/xz=1 y(z-x)/xz=1 y=xz/(z-x) 8. 4/(a+2)-7/(a^2+4a+4) =4/(a+2)-7/((a+2)^2) =(4(a+2)-7)/((a+2)^2) 9.(s+7)/(s+3)-(s-3)/(s+7) =((s+7)^2-(s-3)(s+3))/((s+7)(s+3)) =(s^2+14s+49-s^2+9)/((s+7)(s+3)) =2(7s-29)/((s+7)(s+3)) 10.4/(s^2+5s+4)+s/(s^2+2s+1) =4/((s+1)(s+4))+s/((s+1)^2) =(4(s+1)+s(s+4))/((s+1)^2(s+4)) =(s^2+8s+4)/((s+1)^2(s+4)) =(s+2)^2/((s+1)^2(s+4)) 11.2/(a^2+4a+3)+1/(a+3) =2/((a+3)(a+1))+(a+1)/((a+3)(a+1)) =(a+3)/((a+3)(a+1)) =1/(a+1) 12.9y/(x-4)+y =(9y+(x-4)y)/(x-4) =((x+5)y)/(x-4) 13.7/(a-4)+5/4-a) =7/(a-4)-5/(a-4) =2/(a-4) 14.c/(7c-d)-d/(d-7c) =c/(7c-d)+d/(7c-d) =(c+d)/(7c-d) ...What is number 15 asking? 16.(2/3+1)/(1/3+1) =(5/3)/(4/3) =1.25 17. (2/(x+2))/(4/(x+2)) =(2/(x+2))/(2(2/(x+2))) =1/2 18. (1/6-2/x)/(1/6+1/x) =(x-12)/(x+6) 19.(d^2/4+4d/5)/((d+1)/2) = (5d^2+16d)/(10(d+1)) 20.[(1/x+1) / 1+ (1/x+1)] =[(1/x+1) / (x+2/x+1)] =1/(x+2) 21.[x/x+2] /((x/(x+2)+x) =[x/x+2] /((x+3)/(x+2)) =x/(x+3)
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