Multiple Choice Question (MCQ)

What is the solution (x,y) to the system of equations below?

\begin{alignedat}{2} 3 &x+ &4 &y = -23 \\ 2 & y- & &x = -19 \end{alignedat}

  1. ×

    (-5,-2)

  2. (3,-8)

  3. ×

    (3,-6)

  4. ×

    (9,-6)

Collected in the board: Algebraic equation

Steven Zheng posted 1 week ago


Answer

  1. \begin{alignedat}{2} 3 &x+ &4 &y = -23 \\ 2 & y- & &x = -19 \end{alignedat}

    Multiplying both sides of 2nd equation by 3 gives


    \begin{alignedat}{2} 3 &x+ &4 &y = -23 \\ 6 & y- & 3&x = -57 \end{alignedat}

    Addition of the two equations to cancel term with x

    10y = -80

    y=-8

    Back substitution yields

    x = 3

    B is correct choice


Steven Zheng posted 1 week ago

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