HP 48gII - Manual (Page 218)

Page 6-17
At this point follow the instructions from Chapter 2 on how to use the Equation
Writer to build an equation. The equation to enter in the Eq field should look
like this (notice that we use only one sub-index to refer to the variables, i.e.,
e
xx
is translated as ex, etc. -- this is done to save typing time):
Use the following shortcuts for special characters:
σ: ~‚s α: ~‚a ∆: ~‚c
and recall that lower-case letters are entered by using
~„ before the
letter key, thus, x is typed as ~„x.
Press
`to return to the solver screen. Enter the values proposed above into
the corresponding fields, so that the solver screen looks like this:
With the ex: field highlighted, press
@SOLVE@ to solve for ex: