HP 39g+ User Manual
Page 91
Solve aplet
7-9
3. Use the Plot view to find an initial guess for T. First set
appropriate X and Y ranges in the Plot Setup. Since we
have an equation,
, the plot will
produce two graphs: one for
and one for
. Since we have set
in
this example, one of the graphs will be
.
Therefore, make the
YRNG
–5 to 35. Keep the
XRNG
default of –6.5 to 6.5.
>6+,)7@
SETUP
-
PLOT
*e,> @5 >(17(5@
35
>(17(5@
4. Plot the graph.
>3/27@
5. Move the cursor near the positive (right-side)
intersection. This cursor value will be an initial guess for
T.
*A, to move cursor to
the intersection.
The two points of
intersection show that
there are two solutions
for this equation. However, only positive values for x
make sense, so we want to find the solution for the
intersection on the right side of the y-axis.
6. Return to the Numeric view.
>180@
Note: the T-value is filled
in with the position of the
cursor from the Plot
view.
7. Ensure that the T value is highlighted, and solve the
equation.
TPGW@
X
V
T
A
T
2
Ч
+
Ч
2
⁄
=
Y
X
=
Y
V
T
A
T
2
Ч
+
Ч
2
⁄
=
X
30
=
Y
30
=