Thursday, January 22, 2015

7.2 Systems of Equations & Start of Solving by Substitution

We will wrap up some practice constructing systems of linear equations from word problems.  A hard part can be learning to translate English into Algebra and vice-versa. 

An example would be:

     Small cards cost $3 each and large cards cost $5 each.  The total amount from the
     sale of the cards is $95. 

     We can choose to make:

     x = the number of small cards sold and 
     y = the number of large cards sold.

     In this scenario 3x + 5y = 95 means $3 per small card plus $5 per large card adds up to
     a total of $95 dollars.  

     There are multiple ways of solving this first equation.  It's only when we say the total

     number of cards is 25, translated to x + y = 25 that we have a systems of equations
     with one common answer.

     In this scenario x + y = 25 translates to "the number of small cards plus the number of

     large cards is 25 cards.  Note that cost is not associated with this function.

HW: pgs 380-81 #s 31, 32, *36 (*do a grid/table/equation/graph for 36)

Today, we will also begin solving linear systems by substitution.  Please watch the following videos of me solving #3 & #4 from your HW, copy the work and answers down, and do the remaining HW problems:

AND HW: pg 386 #s 3-7

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