7.2 Substitution Review & 7.3 Elimination

Hope you all had a good weekend!

I corrected your quizzes and saw some consistent errors with regard to substitution.  One was that a number of people solved for variables in both equations and the other was a tendency to solve for y only rather than x.

It's important to note two things:

1. You can solve for either variable in either equation.  Generally, the best thing to do is to identify the variable that will be easiest to isolate.  
2. You only need to solve for one variable (of the four options) and substitute that into the other equation.  No matter which variable you choose, you will get the same answer.

For your classwork/homework please watch the videos below, take notes and then replicate the process of solving for all four variables for #2 (see HW below).

Substitution - pg 386 #15 - solve for first variable, first equation
Substitution - pg 386 #15 - solve for second variable, first equation
Substitution - pg 386 #15 - solve for first & second variables, second equation


HW: pg 386 #2 (solve for each variable in each equation, 4 times, same equation)

1. isolate x in 2x - 3y = 24, then substitute
2. isolate y in 2x - 3y = 24, then substitute
3. isolate x in 2x + y = 8, then substitute
4. isolate y in 2x + y = 8, then substitute

The answer for all of these should be x = 6 and y = -4

Then, for additional homework please:

1. make grids
2. translate the word problem into equations & 
3. solve by elimination

the following problems:

HW: pg 396 #43 & 45 (show grid, equations and solution by elimination)