Maths: Logarithmic?

第一題看不清楚

2.
2 log(x,10) - 4 log(1000,x) = 5
2 log(x,10) - 12 log(10,x) = 5
2 log(x,10) - 12/log(x,10) = 5
2 [log(x,10)]^2 - 5 log(x,10) - 12 = 0
[2 log(x,10) + 3][log(x,10) - 4]=0
log(x,10)= - 3/2 or 4
x = 1/(10√10) or 10000

點樣先可以睇到(清楚D)貼圖嘅題目