A system of equations and its solution are given below.

System A

[tex]\[
\begin{aligned}
-x - 2y & = 7 \\
5x - 6y & = -3
\end{aligned}
\][/tex]

Solution: [tex]\((-3, -2)\)[/tex]

Choose the correct option that explains what steps were followed to obtain the system of equations below.

System B

[tex]\[
\begin{aligned}
-x - 2y & = 7 \\
-16y & = 32
\end{aligned}
\][/tex]

A. To get System B, the second equation in System A was replaced by the sum of that equation and the first equation multiplied by [tex]\(-5\)[/tex]. The solution to System B will not be the same as the solution to System A.

B. To get System B, the second equation in System A was replaced by the sum of that equation and the first equation multiplied by [tex]\(3\)[/tex]. The solution to System B will be the same as the solution to System A.

C. To get System B, the second equation in System A was replaced by the sum of that equation and the first equation multiplied by [tex]\(-6\)[/tex]. The solution to System B will not be the same as the solution to System A.

D. To get System B, the second equation in System A was replaced by the sum of that equation and the first equation multiplied by [tex]\(5\)[/tex]. The solution to System B will be the same as the solution to System A.



Answer :

To determine how System B was derived from System A, let's carefully review the necessary steps. We have:

System A:
[tex]\[ \begin{aligned} -x - 2y &= 7 \quad \text{(Equation 1)} \\ 5x - 6y &= -3 \quad \text{(Equation 2)} \end{aligned} \][/tex]

System B:
[tex]\[ \begin{aligned} -x - 2y &= 7 \quad \text{(Equation 3)} \\ -16y &= 32 \quad \text{(Equation 4)} \end{aligned} \][/tex]

We need to ascertain what operations on System A will result in System B.

First, observe that Equation 3 is identical to Equation 1, so the transformation must involve Equation 2 being replaced by a new equation derived from Equation 1 and Equation 2.

To transform Equation 2 (5x - 6y = -3) into Equation 4 (-16y = 32), notice that the new equation needs to eliminate the [tex]\(x\)[/tex] term and result in an equation involving only [tex]\(y\)[/tex]. This can be achieved by combining Equation 2 with a modified version of Equation 1.

Let's multiply Equation 1 by 5:
[tex]\[ -5x - 10y = 35 \quad \text{(Equation 1 multiplied by 5)} \][/tex]

Now, add this new equation to Equation 2:
[tex]\[ \begin{aligned} (-5x - 10y) + (5x - 6y) &= 35 + (-3) \\ -5x + 5x - 10y - 6y &= 35 - 3 \\ -16y &= 32 \end{aligned} \][/tex]

Equation 4 (-16y = 32) is exactly the result we get. Hence, the correct transformation involves replacing Equation 2 with the sum of Equation 2 and Equation 1 multiplied by 5.

Thus, the correct option is:
D. To get system B, the second equation in system A was replaced by the sum of that equation and the first equation multiplied by 5. The solution to system B will be the same as the solution to system A.

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