#### 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 3 months ago

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 3 months ago

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