Texas Instruments TI-89 Titanium Short User Manual

90 Activities
Deriving the Quadratic Formula
This activity shows you how to derive the quadratic formula:
x =
Detailed information about using the functions in this example can be
found in Symbolic Manipulation.
3. Define the expression for side c in terms of
w and store it in c(w).
Enter: Define c(w)= ‡(a(w)^2+b(w)^2)
4. Use the zeros( ) function to compute the
zeros of the first derivative of c(w) to find
the minimum value of
c(w).
Note: The maximum length of the pole is
the minimum value of c(w).
5. Compute the exact maximum length of the
pole.
Enter: c (2 ±)
6. Compute the approximate maximum length
of the pole.
Result: Approximately 20.8097 feet.
Note: Use the auto-paste feature to copy
the result from step 4 to the entry line
inside the parentheses of c( ) and press 8
¸.
b
–
b
2
4ac–±
2a
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Texas Instruments TI-89 Titanium Specifications

General

Display Type	LCD
Display Resolution	160 x 100 pixels
CPU	Motorola 68000
CPU Speed	16 MHz
RAM	256 KB
Flash ROM	2.7 MB
Programming Language	TI-BASIC, Assembly
Power Source	4 AAA batteries
Connectivity	I/O port
Dimensions	7.5 x 3.5 x 1 inches