BELL RINGER

Yesterday you learned 3

different ways to solve

systems of linear equations.

Do you have a preference on

how to solve systems?

Explain.

SYSTEMS OF LINEAR EQUATIONS CONT.

Friday, February 6, 2014

QUICK REVIEW

You can solve systems of

linear equations by

graphing, substitution, or

elimination… but when do

you use which one?

WHEN DO YOU GRAPH?

If all equations are in the

form y =, then it is easiest to

graph (if you have a graphing

calculator), but you can always

graph if you solve for y first.

WHEN DO YOU SUBSTITUTE?

If only one equation is

solved for one variable,

then it is usually easiest to

use substitution; however,

you can always solve one

equation for a variable and

then substitute.

WHEN DO YOU USE ELIMINATION?

If the systems are already in

standard form (Ax + By = C),

then it’s easiest to use

elimination. Again, you can

always change the equations to

standard form and then use

elimination.

What are you going to

use for your variables?

How do you set up the

problem?

SYSTEMS IN WORD PROBLEMS

SOLVING BY MATRICES

First, get the system in standard form (Ax +

By = C). Then multiply the inverse of the

coefficient matrix by the constant matrix to

give you the value of the variables.

If you get an error message “ERR:

SINGULAR MAT”, then the equations are either

parallel lines or the same line, so there is no

solution or infinite solutions (you have to

check).

MATRIX EXAMPLES

1. 6x + 2y = 11 2. 6a – 9b = -

18

3x – 8y = 1 8a – 12b

= 24

Brenda’s school is selling tickets to a

spring musical. On the first day of ticket

sales the school sold 3 senior citizen

tickets and 9 child tickets for a total of

$75. The school took in $67 on the

second day by selling 8 senior tickets and

5 child tickets. What is the price each of

one senior citizen ticket and one child

ticket?

SYSTEMS IN WORD PROBLEMS

SYSTEMS IN WORD PROBLEMS

A boat traveled 336 miles

downstream and back. The trip

downstream took 12 hours. The

trip back took 14 hours. What is

the speed of the boat in still

water? What is the speed of the

current?

CLASSWORK

Solve the Odd Numbered systems

using any of the 4 methods you choose.

Feel free to use the same method for

each problem, but you are not limited

in your choice. SHOW YOUR WORK

HOMEWORK

Solve the Even Numbered systems

using any of the 4 methods you

choose. Feel free to use the same

method for each problem, but you are

not limited in your choice. SHOW

YOUR WORK