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3x_5y=0 9x=2y+7

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3x_5y=0 9x=2y+7
  • 1 answers

Sia ? 6 years, 3 months ago

  1. By Elimination method,
    The given system of equations is :
    3 x - 5 y - 4 = 0............(1)
    9 x = 2 y + 7
    9 x - 2 y - 7 = 0.............(2)
    Multiplying equation (1) by 3, we get
    9 x - 15 y - 12 = 0.............(3)
    Subtracting equation (3) from equation (2) , we get
    13 y + 5 = 0
    {tex}\Rightarrow \quad 13 y = - 5 \Rightarrow y = \frac { - 5 } { 13 }{/tex}
    Substituting this value of y in equation (1), we get
     {tex}3 x - 5 \left( \frac { - 5 } { 13 } \right) - 4 = 0{/tex}
    {tex}\Rightarrow \quad 3 x + \frac { 25 } { 13 } - 4 = 0 \Rightarrow 3 x - \frac { 27 } { 13 } = 0{/tex}
    {tex}\Rightarrow \quad 3 x = \frac { 27 } { 13 } \Rightarrow x = \frac { 9 } { 13 }{/tex}
    So, the solution of the given system of equation is
     {tex}x = \frac { 9 } { 13 } , y = \frac { - 5 } { 13 }{/tex}
  2. By Substitution method:
    The given system of equation is:
    3 x - 5 y - 4 = 0.............(1)
    9 x = 2 y + 7...................(2)
    From equation (2),
    {tex}x = \frac { 2 y + 7 } { 9 }{/tex}..................(3)
    Substituting this value of x in equation(1), we get
    {tex}3 \left( \frac { 2 y + 7 } { 9 } \right) - 5 y - 4 = 0{/tex}
    {tex}\Rightarrow \quad \frac { 2 y + 7 } { 3 } - 5 y - 4 = 0{/tex}
    {tex}\Rightarrow \quad 2 y + 7 - 15 y - 12 = 0{/tex}
    {tex}\Rightarrow{/tex} -13y - 5 = 0
     {tex}\Rightarrow{/tex} 13y = -5
    {tex}\Rightarrow \quad y = \frac { - 5 } { 13 }{/tex}
    Substituting this value of y in equation(3), we get
    {tex}x = \frac { 2 \left( \frac { - 5 } { 13 } \right) + 7 } { 9 } = \frac { - \frac { 10 } { 13 } + 7 } { 9 } = \frac { - 10 + 91 } { 117 } = \frac { 81 } { 117 } = \frac { 9 } { 13 }{/tex}​​​​
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