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Follow the directions to solve the system of equations by elimination. 8x + 7y = 39 4x – 14y = –68 Multiply the first equation to enable the elimination of the y-term. Add the equations to eliminate the y-terms. Solve the new equation for the x-value. Substitute the x-value back into either original equation to find the y-value. Check the solution. The solution to the system of equations is (, ).

Respuesta :

8x +7y = 39 multiply everything by 2
2(8x +7y = 39)
16x +14y = 78
+4x - 14y= -68
-------------------------
20x = 10
20x /20 = 10/20
x = 1/2

Plug x into first formula
8 x + 7y =39
8(1/2) 7y=39
4+ 7y =39
4-4+7y =39-4
7y =35
7y/7 = 35/7
y = 5
(1/2, 5)

The given system of linear equations has a unique solution. The solution to the system of equations is [tex](\frac{1}{2}, 5)[/tex].

Given equations:

    [tex]8x+7y=39[/tex]          ...........(i)

    [tex]4x-14y=-68[/tex]     ...........(ii)

Multiply the first equation by 2 to enable the elimination of the y-term.

    [tex]2(8x+7y=39)\\16x+14y=78[/tex]    ...........(iii)

Add the equations (ii) and (iii) to eliminate the y-terms

    [tex]4x-14y=-68\\16x+14y=78[/tex]

------------------------------

    [tex]20x=10[/tex]

or  [tex]x=\frac{10}{20}[/tex]

or  [tex]x=\frac{1}{2}[/tex]

Plug x into equation (i) to find the x-value

      [tex]8(\frac{1}{2}) +7y=39\\4+7y=39\\7y=39-4\\7y=35\\y=\frac{35}{7} \\y=5[/tex]

Check the solution

     [tex]8x+7y=39[/tex]

For

       [tex]x=\frac{1}{2} \\y=5[/tex]

  [tex]8(\frac{1}{2} )+7(5)=39\\4+35=39\\39=39[/tex]

 LHS = RHS

Therefore, the solution to the system of equations is [tex](\frac{1}{2} , 5)[/tex].

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