Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
2. Solving Systems of Linear Equations by Substitution
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Exercise 32 Page 228

Practice makes perfect
a The point of intersection of a system is the x- and y-coordinates where the lines cross. We can determine this point from a graph by looking at the coordinates where the graphs intersect.


From the graph, we can see that the lines cross at the point (4,5).

b To verify or to find an exact solution, we can solve the system algebraically. It is possible to solve the given system algebraically by using the Substitution Method.
y=x+1 y=6- 14x To solve the system we can substitute (x+1) for y in the second equation and solve for x. Once we know x, we can substitute that value into either equation to solve for y.
y=x+1 & (I) y=6-1/4x & (II)
y=x+1 x+1=6-1/4x
â–Ľ
(II): Solve for x
y=x+1 1/4x+x+1=6
y=x+1 1/4x+ 4x4+1=6
y=x+1 x/4+ 4x4+1=6
y=x+1 5x/4+1=6
y=x+1 5x/4=5
y=x+1 5x=20
y=x+1 x=4
The x-coordinate of the solution to the system is 4. To determine the corresponding y-value, we can substitute x=4 into the first equation and solve for y.
y=x+1 x=4
y= 4+1 x=4
y=5 x=4
The y coordinate of the solution to the system is 5. From the work above, we have verified that (4,5) is the solution to the system.