HP 50G, User Manual

Page: 91 / 887

Page 2-31
and the variable of differentiation. To fill these input locations, use the following
keystrokes:
~„t™~‚a*~„tQ2
™™+~‚b*~„t+~‚d
The resulting screen is the following:
To see the corresponding expression in the line editor, press
‚—
and the
A
soft menu key, to show:
This indicates that the general expression for a derivative in the line editor or in
the stack is:
∂
variable ( function of variables )
Press
`
to return to the Equation Writer. The resulting screen is not the
derivative we entered, however, but its symbolic value, namely,
To recover the derivative expression use
‚¯
. To evaluate the derivative
again, you can use the
D
soft menu key. This shows again that
.
Second order derivatives are possible, for example:
which evaluates to:
β α δ β α
+ ⋅ = + ⋅ − ⋅
t t t
dt
d
2 ) (
2