Question

A. x = –4

Answer 1

Please, please, post only ONE question at a time.  The way Brainly is set up, it's very difficult to conclude one problem and then move on to the next in the same session.

Solve y = log3243.  I must make the assumption here that you mean:

Solve y = (log to the base 3) of 243.

Solve y = (log   243   in better, more compact form.
                      3

If you recognize that 243 is an integer power of 3, the problem becomes much easier.  
                  2             3            4                  5
Note that 3   = 9,    3   = 27, 3   =81, and 3   = 243.

Also note that the log function and the exponential function are inverses of one another, and that inverse functions "undo" each other.
                      x
Thus, log    3     is simply x.
               3
                                           5
Thus, log    243  =  log     3    = 5 (answer).
                3                   3

Please repost the rest of your questions, one at a time, and then I will gladly help you with them.