HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010

Example 5: Solving equations
Solve the equation
x
4
13−= , giving
i) real solutions and
ii) complex solutions.
From within the CAS, press
SHIFT MODES to access the configuration
menu and ensure that you are in real mode by, if necessary,
un-
ing Complex mode, as shown right.
Now use the
SOLVEVX function, typing:
The
SOLVEVX function assumes that the active variable is being used.
The default active variable is
X and if no = sign is included then the
expression is assumed to be equal to zero. The related function of
SOLVE has a second parameter which allows you to define the variable
to be solved for if it is not
X.
Changing to
Complex mode in the configuration menu will allow you
to find the other two imaginary solutions as shown right.
Example 6: Solving simultaneous equations
+
⎧
xy=−3
Solve the following system of equations:
⎨
⎩
xy
−
1
=
In the CAS, enter: LINSOLVE(X+Y+3 AND X–Y+1, X AND Y).
Note that when entering the two equations you must highlight the first
one before pressing
AND (obtained via SHIFT (-)). If you don’t do this
then the CAS will assume that the
AND applies only to the 3 and place
brackets incorrectly accordingly.
Alternatively you can use
X+Y=-3 AND X=Y-1 instead of the
expressions. Again, you must highlight the entire first equation before
adding the
AND.
The result is:
(X=–2) AND (Y=–1)
LINSOLVE can be used for any number of simultaneous variables. If
you set
Step by step mode in the configuration menu then the CAS will
show the solution process using row manipulation of an augmented
matrix.
346