Quote (Dorieus @ Sep 22 2013 06:36am)
I most likely did something fucking illegal and all mathematicians would like to hang me, but..
(7x-2)^(1/3) + (7x+5)^(1/3) = 3
1/3*log(7x-2) + 1/3*log(7x+5) = log3
log[(7x-2)/3] + log[(7x+5)/3] = log 3
Then I just toss those logs away and get
(7x-2)/3 + (7x+5)/3 = 3
(14x+3)/3 = 3
14x+3=9
14x=6
x=6/14
x=3/7
Which gives the right answer, but I have a very strong feeling I did something I shouldn't have done when I just wiped out the logs...
(And probably when I involved them...)
you did the right steps, but throwing out the logs isn't how you got rid of them lmao
Due to Logs not being something you can multiply / divide, you can't just divide them away. I'm pretty sure there is something you can do to cancel them out though. I know ln and e cancel, sure there is something for the logs.