HP 39gs User Manual page 87

H I N T
Solve the
unknown
variable
Plot the
equation
Solve aplet
4. Enter the values for the known variables.
2 7 7 8
1 6 6 7
1 0 0
If the Decimal Mark setting in the Modes input form
( ) is set to Comma, use
MODES
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
2.47 m/s .
Because the variable A in the equation is linear we
know that we need not look for any other solutions.
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
Y = 771.7284
The other graph will be
U = 16.67
and
Y = 200A + 277.8889
desired solution is the value of A where these two
lines intersect.
2 2
V = U
2
Y = V V
, with
. This graph will be a horizontal line.
2
Y = U +
D = 100
, that is,
. This graph is also a line. The
instead of .
+ 2AD
.
= 27.78
, that is,
2AD
, with
7-3