HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 354

To aid in this, we will change to the small, font, c earing the screen first.

Page 354 highlights

vi. Clear the current contents of the screen using SHIFT ALPHA CLEAR. Then perform the same definition assignment for Y1(t) as the imaginary part of M. ALPHA M MATH ENTER ENTER Note: As before, the button jumps to the first function with that letter (L), in this case IM. ENTER SHIFT = ALPHA Y 1 ( ALPHA SHIFT T SHIFT SHIFT ENTER vii. In order to show that the function is symmetrical about the x axis we need to show that (X1(-t),Y1(-t)) is equivalent algebraically to (X1(t), -Y1(t)). Purely for convenience we will display X1(t)=X1(-t) and evaluate each side. The = is not used to solve anything but just to display both at once for comparison so that it can be seen whether or not they are equal as required. To aid in this, we will change to the small font, clearing the screen first. SHIFT ALPHA CLEAR ALPHA X 1 ( SHIFT ALPHA T SHIFT = ALPHA X 1 ( SHIFT ALPHA T (-) SHIFT ENTER As can be seen, the two are algebraically equivalent. We now check the same equality for Y1, again clearing the screen first. SHIFT ALPHA CLEAR ALPHA Y 1 ( SHIFT ALPHA T SHIFT = ALPHA Y 1 ( SHIFT ALPHA T (-) SHIFT ENTER Again it is clear that the condition that Y1(t)= -Y1(-t) has been met. Therefore we can conclude that the graph is symmetrical about the x axis. 354

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vi.
Clear the current contents of the
screen using
SHIFT ALPHA CLEAR
. Then perform the same definition assignment for
Y1(t)
as the
imaginary part of
M
.
ALPHA M
MATH
ENTER ENTER
Note:
As before, the
button jumps to the first
function with that letter (
L
), in this case
IM
.
ENTER
SHIFT =
ALPHA Y 1 ( ALPHA SHIFT T
SHIFT
SHIFT
ENTER
vii.
In order to show that the function is symmetrical about the x axis we need to show that
(X1(-t),Y1(-t))
is
equivalent algebraically to
(X1(t), -Y1(t))
. Purely for convenience we will display
X1(t)=X1(-t)
and
evaluate each side.
The = is not used to solve anything but just to display both at once for comparison so
that it can be seen whether or not they are equal as required.
To aid in this, we will change to the small
l
SHIFT ALPHA CLEAR
ALPHA X 1 ( SHIFT ALPHA T
SHIFT =
T (-)
SHIFT
ENTER
We now
font, c earing the screen first.
ALPHA
X
1
(
SHIFT
ALPHA
As can be seen, the two are algebraically equivalent.
check the same equality for
Y1
, again clearing the screen first.
SHIFT ALPHA CLEAR
ALPHA Y 1 ( SHIFT ALPHA T
SHIFT = ALPHA
Y
1
(
SHIFT
ALPHA
T (-)
SHIFT
ENTER
Again it is clear that the condition that
Y1(t)= -Y1(-t)
has been met.
Therefore we can conclude that the
graph is symmetrical about the x axis.
354