Chapter 7 Notetaking Guide.pdf
Chapter 7 Notetaking Guide.pdf
Chapter 7 Notetaking Guide.pdf
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•<br />
So ving Li ear Systems<br />
by Subs itution<br />
Goal<br />
Solve a linear system by substitution.<br />
SOLVING A LINEAR SYSTEM BY SUBSTITUTION<br />
Step 1 Solve one of the equations for one"of its<br />
----<br />
Step 2 Substitute the expression from Step 1 into the other<br />
equation and solve for the<br />
------<br />
I Step 3 Substitute the value from into the revised equation<br />
from and sOllve.<br />
Step 4 Check the solution in each of the<br />
equations.<br />
Example 1<br />
Substitution Method: Solve for y First<br />
When you use<br />
I the substitution<br />
method, you can<br />
check the solution<br />
by substituting it for<br />
x and for y in each<br />
of the original<br />
equations. You can<br />
also use a graph to<br />
check your solution.<br />
Solve the linear system. 4x + Y = -5 Equation 1<br />
1. Solve for y in Equation 1.<br />
4x + Y = -5<br />
y =<br />
3x - y = 5 Equation 2<br />
Ori'ginal Equation 1<br />
Revised Equation 1<br />
2. Substitute for y in Equation 2 and find the<br />
value of x.<br />
3x - y = 5 Write Equation 2.<br />
3x - ( ) =<br />
----<br />
5 Substitute for y.<br />
x + = 5 Simplify.<br />
x= Subtract from each side.<br />
x =<br />
Divide each side by<br />
3. Substitute for x in the revised Equation 1 and find the value<br />
of y.<br />
y= =<br />
-----<br />
4. Check that (_, __) is a solution by sUbstituting _ for x and<br />
fory in each of the original equations.<br />
Lesson 7.2 . Algebra 1 Concepts and Skills Notetaklng <strong>Guide</strong> 145<br />
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