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Answer Key 3.6

  1. \(m=2\)
  2. \(m=-\dfrac{2}{3}\)
  3. \(m=4\)
  4. \(m=-10\)
  5. \(\begin{array}{rrrrlrrr}
    \\ \\ \\ \\
    x&-&y&=&4&&& \\
    -x&&&&-x&&& \\
    \hline
    &&(-y&=&-x&+&4)&(-1) \\
    &&y&=&x&-&4& \\
    &&m&=&1&&&
    \end{array}\)
  6. \(\begin{array}{rrrrlrrr}
    \\ \\ \\ \\ \\ \\ \\ \\
    6x&-&5y&=&20&&& \\
    -6x&&&&-6x&&& \\
    \hline
    &&\dfrac{-5y}{-5}&=&\dfrac{-6x}{-5}&+&\dfrac{20}{-5}& \\ \\
    &&y&=&\dfrac{6}{5}x&-&4& \\ \\
    &&m&=&\dfrac{6}{5}&&&
    \end{array}\)
  7. \(\begin{array}{rrlrrr}
    \\ \\ \\ \\ \\
    y&=&\dfrac{1}{3}x&&& \\ \\
    \therefore m&=&\dfrac{1}{3} &&& \\
    m_{\perp} &=&-1&\div &\dfrac{1}{3}&\text{or} \\
    m_{\perp}&=&-3 &&&
    \end{array}\)
  8. \(\begin{array}{lrlrrrr}
    \\ \\ \\ \\
    m&=&-\dfrac{1}{2} &&&& \\
    m_{\perp} &=&-1&\div &-\dfrac{1}{2}&&\\ \\
    m_{\perp}&=&-1 &\cdot &-\dfrac{2}{1}&=& 2
    \end{array}\)
  9. \(\begin{array}{lrlrrrr}
    \\ \\ \\ \\
    m&=&-\dfrac{1}{3} &&&& \\
    m_{\perp} &=&-1&\div &-\dfrac{1}{3}&&\\ \\
    m_{\perp}&=&-1 &\cdot &-\dfrac{3}{1}&=& 3
    \end{array}\)
  10. \(\begin{array}{lrlrrrr}
    \\ \\ \\ \\
    m&=&\dfrac{4}{5} &&&& \\
    m_{\perp} &=&-1&\div &\dfrac{4}{5}&&\\ \\
    m_{\perp}&=&-1 &\cdot &\dfrac{5}{4}&=& -\dfrac{5}{4}
    \end{array}\)
  11. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\ \\ \\
    x&-&3y&=&-6& \\
    -x&&&&-x&& \\
    \hline
    &&\dfrac{-3y}{-3}&=&\dfrac{-x}{-3}&-&\dfrac{6}{-3} \\ \\
    &&y&=&\dfrac{1}{3}x&+&2 \\
    &&m_{\perp}&=&-1&\div &\dfrac{1}{3} \\
    &&m_{\perp}&=&-3&&
    \end{array}\)
  12. \(\begin{array}{rrrrrrr}
    \\ \\ \\ \\ \\ \\
    3x&-&y&=&-3& \\
    -3x&&&&-3x&& \\
    \hline
    &&-y&=&-3x&-&3 \\
    &&y&=&3x&+&3 \\
    &&m_{\perp}&=&-1&\div &3 \\
    &&m_{\perp}&=&-\dfrac{1}{3}&&
    \end{array}\)
  13. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    m&=&\dfrac{2}{5}&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1) \\
    y&-&4&=&\dfrac{2}{5}(x&-&1) \\ \\
    y&-&4&=&\dfrac{2}{5}x&-&\dfrac{2}{5} \\ \\
    &+&4&&&+&4 \\
    \hline
    &&y&=&\dfrac{2}{5}x&+&\dfrac{18}{5}
    \end{array}\)
  14. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\
    m&=&-3&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1) \\
    y&-&2&=&-3(x&-&5) \\
    y&-&2&=&-3x&+&15 \\
    &+&2&&&+&2 \\
    \hline
    &&y&=&-3x&+&17
    \end{array}\)
  15. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    m&=&\dfrac{1}{2}&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1) \\
    y&-&4&=&\dfrac{1}{2}(x&-&3) \\ \\
    y&-&4&=&\dfrac{1}{2}x&-&\dfrac{3}{2} \\ \\
    &+&4&&&+&4 \\
    \hline
    &&y&=&\dfrac{1}{2}x&+&\dfrac{5}{2}
    \end{array}\)
  16. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    m&=&\dfrac{4}{3}&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1) \\
    y&-&-1&=&\dfrac{4}{3}(x&-&1) \\ \\
    y&+&1&=&\dfrac{4}{3}x&-&\dfrac{4}{3} \\ \\
    &-&1&&&-&1 \\
    \hline
    &&y&=&\dfrac{4}{3}x&-&\dfrac{7}{3}
    \end{array}\)
  17. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    m&=&-\dfrac{3}{5}&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1) \\
    y&-&3&=&-\dfrac{3}{5}(x&-&2) \\ \\
    y&-&3&=&-\dfrac{3}{5}x&+&\dfrac{6}{5} \\ \\
    &+&3&&&+&3 \\
    \hline
    &&y&=&-\dfrac{3}{5}x&+&\dfrac{21}{5}
    \end{array}\)
  18. \(\begin{array}{rrrrlrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    m&=&\dfrac{1}{3}&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1) \\
    y&-&3&=&\dfrac{1}{3}(x&-&-1) \\ \\
    y&-&3&=&\dfrac{1}{3}x&+&\dfrac{1}{3} \\ \\
    &+&3&&&+&3 \\
    \hline
    &&y&=&\dfrac{1}{3}x&+&\dfrac{10}{3}
    \end{array}\)
  19. \(\begin{array}{rrrrrrrrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    -x&+&y&=&1&&&& \\
    +x&&&&+x&&&& \\
    \hline
    &&y&=&x&+&1&& \\
    &&\therefore m&=&1&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1)&& \\
    y&-&-5&=&1(x&-&1)&& \\
    y&+&5&=&x&-&1&& \\
    -y&-&5&&-y&-&5&& \\
    \hline
    &&0&=&x&-&y&-&6
    \end{array}\)
  20. \(\begin{array}{rrrrrrrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    -x&+&2y&=&2&&& \\
    +x&&&&+x&&& \\
    \hline
    &&2y&=&x&+&2& \\
    &\text{or}&y&=&\dfrac{1}{2}x&+&1& \\ \\
    &&\therefore m&=&-2&&& \\ \\
    y&-&y_1&=&m(x&-&x_1)& \\
    y&-&-2&=&-2(x&-&1)& \\
    y&+&2&=&-2x&+&2& \\
    -y&-&2&&-y&-&2& \\
    \hline
    &&(0&=&-2x&-&y)&(-1) \\
    &&0&=&2x&+&y&
    \end{array}\)
  21. \(\begin{array}{rrrrrrrrrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    5x&+&y&=&-3&&&&& \\
    -5x&&&&-5x&&&&& \\
    \hline
    &&y&=&-5x&-&3&&& \\
    &&\therefore m&=&-5&&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1)&&& \\
    y&-&2&=&-5(x&-&5)&&& \\
    y&-&2&=&-5x&+&25&&& \\
    -y&+&2&&-y&+&2&&& \\
    \hline
    &&(0&=&-5x&-&y&+&27)&(-1) \\
    &&0&=&5x&+&y&-&27&
    \end{array}\)
  22. \(\begin{array}{rrrrrrrrrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    -x&+&y&=&1&&&&& \\
    +x&&&&+x&&&&& \\
    \hline
    &&y&=&x&+&1&&& \\
    &&\therefore m&=&-1&&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1)&&& \\
    y&-&3&=&-1(x&-&1)&&& \\
    y&-&3&=&-x&+&1&&& \\
    -y&+&3&&-y&+&3&&& \\
    \hline
    &&(0&=&-x&-&y&+&4)&(-1) \\
    &&0&=&x&+&y&-&4&
    \end{array}\)
  23. \(\begin{array}{rrrrrrrrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    -4x&+&y&=&0&&&& \\
    +4x&&&&+4x&&&& \\
    \hline
    &&y&=&4x&&&& \\
    &&\therefore m&=&4&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1)&& \\
    y&-&2&=&4(x&-&4)&& \\
    y&-&2&=&4x&-&16&& \\
    -y&+&2&&-y&+&2&& \\
    \hline
    &&0&=&4x&-&y&-&14
    \end{array}\)
  24. \(\begin{array}{rrrrrrrrrr}
    \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\ \\
    3x&+&7y&=&0&&&&& \\
    -3x&&&&-3x&&&&& \\
    \hline
    &&7y&=&-3x&&&&& \\
    &\text{or}&y&=&-\dfrac{3}{7}x&&&&& \\ \\
    &&\therefore m&=&\dfrac{7}{3}&&&&& \\ \\
    y&-&y_1&=&m(x&-&x_1)&&& \\
    y&-&-5&=&\dfrac{7}{3}(x&-&-3)&&& \\ \\
    y&+&5&=&\dfrac{7}{3}x&+&7&&& \\ \\
    -y&-&5&&-y&-&5&&& \\
    \hline
    &&(0&=&\dfrac{7}{3}x&-&y&+&2)&(3) \\ \\
    &&0&=&7x&-&3y&+&6&
    \end{array}\)
  25. \(y=-3\)
  26. \(x=-5\)
  27. \(x=-3\)
  28. \(y=0\)
  29. \(y=-1\)
  30. \(x=2\)
  31. \(x=-2\)
  32. \(y=-4\)
  33. \(y=3\)
  34. \(x=-3\)
  35. \(x=5\)
  36. \(y=-1\)

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