Very simple symbol question regarding a logarithmic function (I can't find it)

[singleton]

Well I have this leftwards arrow in my book describing the solution to a logarithmic function and I've not seen it thus far and (if I was ever introduced to it) have since forgot what it means!

When asked to find log(3)9
3^x = 9
3^x = 3^2
<--x = 2
log(3)9 = 2

I'm not sure what the leftwards arrow beside the x is for :(

Please forgive my logarithmic notation, I'm aweful with latex(?) so please note that 3 is the base (so I separated it in brackets).

 

[Tide]

I don't think there is anything "standard" there. It's just the author's way of telling you to substitute the value x = 2 into the equation or that x = 2 is the solution.

 

[jcsd]

I'll take a guess: "it follows from".