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Solve the following systems by any method.

 

4x + 7y = 6

9x - 2y = 49 

 

 

 

 

and

 

 

 

 

3x - y = 4

y = 2x -2

 Apr 30, 2019
 #1
avatar+106515 
+1

4x + 7y = 6

9x - 2y = 49 

 

Let's choose to eliminate y.....we can do this by multiplying the first equation by 2   and the second by 7.....do you see why this might work, SMM???.....so we have

 

8x + 14y = 12

63x - 14y = 343          add these   and notice that "y" disappears

 

71x  =  355       divide both sides by 71

x  = 5       

 

Can you take it from here and find y ???

 

 

 

3x - y = 4

y = 2x -2      easier than the first one......we have an explicit expression for y......so....sub the second equation into the first for y   and we have

 

3x - [ 2x - 2 ]  = 4       simplify

3x - 2x + 2  = 4

x + 2  = 4

x = 2

 

Sub this into the second equation to find y

 

cool cool cool

 Apr 30, 2019

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