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Adam and Devin both solve this system of equations:

 

y = -0.5x + 3

y = 1.5x + 0.2

 

Adam's solution is (1.4, 2.3). Devin's solution is (2.2, 1.7). They graph the equations to check their work. 

 

Based on the graph, whose solution is more likely to be correct?

 Jan 6, 2019
 #1
avatar+701 
+3

I do not think we need a graph for this. We can just solve the system of equations to find out who is right. 

 

      y = -0.5x + 3

-     y = 1.5x + 0.2

_______________

      0 = -2x + 2.8 --> 2x = 2.8 --> x = 1.4

 

Inserting x = 1.4 into the equation y = 1.5x + 0.2, we have y = 2.1 + 0.2 --> y = 2.3. The solution is (1.4, 2.3)

 

Adam's solution is correct.

 

- PM

 #2
avatar+701 
+2

If you want to check Devin's solution, we can use the same equation of y = 1.5x + 0.2.

 

x = 2.2 and y = 1.7. 

 

We have 1.7 = 1.5(2.2) + 0.2 --> 1.7 = 3.3 + 0.2 --> 1.7 = 3.5. This is not true, so Devin's solution is not correct. Adam's is correct.


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