Hint, Solve the unknown variable, Plot the equation – HP 39g+ User Manual
Page 87
Solve aplet
7-3
4. Enter the values for the known variables.
2 7
7 8
1 6
6 7
1 0 0
H I N T
If the Decimal Mark setting in the Modes input form
(
MODES
) is set to Comma, use
instead of
.
Solve the
unknown
variable
5. Solve for the unknown variable (A).
Therefore, the acceleration needed to increase the
speed of a car from 16.67 m/sec (60 kph) to 27.78
m/sec
(100 kph) in a distance of 100 m is approximately
2.47 m/s
2
.
Because the variable A in the equation is linear we
know that we need not look for any other solutions.
Plot the
equation
The Plot view shows one graph for each side of the
selected equation. You can choose any of the
variables to be the independent variable.
The current equation is
.
One of these is
, with
, that is,
. This graph will be a horizontal line.
The other graph will be
, with
and
, that is,
. This graph is also a line. The
desired solution is the value of A where these two
lines intersect.
V
2
U
2
2AD
+
=
Y
V
2
=
V
27.78
=
Y
771.7284
=
Y
U
2
2AD
+
=
U
16.67
=
D
100
=
Y
200A 277.8889
+
=