6*4^x-13*6^x+6*9^x=0
Solutions can be seen more easily from the following:
.
Integer solutions are x = + or - 1
http://www.wolframalpha.com/input/?i=6*4%5Ex-13*6%5Ex%2B6*9%5Ex%3D0
Thanks Alan
I would not have thought to do that.
How can you tell that there will be another solution as as x→−∞ ?
Because, if you look at the original form of the equation, 4-∞ = 0, 6-∞ = 0 and 9-∞ = 0 i.e. each of the terms on the LHS is individually zero.
In that limit my rearranged version of the equation doesn't hold, because a divide by zero would be involved.
Thanks Alan, that makes sense :)