Texas Instruments TI-89 Manual Book page 90

Solving an Equation
Note: An operation such as
| 2 Ù subtracts 2x from
both sides.
Solving a System of
Linear Equations
Note: The simult and rref
matrix functions are not on
the „ Algebra menu. Use
2 I 4 or the Catalog.
( „
Use the ) function to solve an equation for a specified
solve 1
variable.
solve(equation, var)
Solve x + y ì 5 = 2x ì 5y
for .
x
Notice that displays
solve
only the final result.
To see intermediate results, you can manually solve the equation
step-by-step.
x « y | 5 Á 2x | 5y
| 2 x
| y
« 5
p · 1
Consider a set of two equations with
two unknowns:
To solve this system of equations, use any of the following methods.
Method
Use the function
solve
for a one-step solution.
Use the function
solve
with substitution ( | )
for step-by-step
manipulation.
Use the function
simult
with a matrix.
Use the function
rref
with a matrix.
2x ì 3y = 4
ë x + 7y = ë 12
Example
solve ( 2xì3y=4 and ëx+7y=ë12,{x,y}
Refer to the preview at the beginning of
this chapter, which solved for
and y = ë 20/11 .
Enter the coefficients as a matrix and the
results as a constant column matrix.
Enter the coefficients as an augmented
matrix.
Chapter 3: Symbolic Manipulation
)
x = ë 8/11
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