10th Class Mathematics Solved Paper - Mathematics-2015 Term-I

  • question_answer
    Solve by elimination:
    \[3x-y=7\]
    \[2x+5y+1=0\]

    Answer:

    \[3x-y=7\]                                                         ...(i)
    \[2x+5y=-1\]                                                                 ...(ii)
    Multiplying equation (i) by 5 and solving it with equation (ii), we get
                            \[_{\begin{smallmatrix}  15x\,-\,5y\,=\,35 \\  \overline{17x\,\,\,\,\,\,\,\,\,\,\,\,\,=\,34\,\,} \end{smallmatrix}}^{2x\,\,+\,\,5y\,\,=\,\,-1}\]
                                                                            (Adding)
    \[\Rightarrow x=\frac{34}{17}=2\]
    Putting the value of x in (i), we have
                            \[3(2)-y=7\]
    \[\Rightarrow 6-y=7\Rightarrow -y=7-6\]
    \[\Rightarrow y=-1\]
    \[\therefore \,\,x=2,y=-1\]


adversite


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