Multiply the 2nd equation by -4. What value belongs in the green box?

[tex]\[
\begin{array}{rr}
-2x + 4y = 15 \\
3x + y = 2 \\
(3x + y = 2) \xrightarrow{\text{multiply by } -4}
\end{array}
\][/tex]

[tex]\[
\begin{array}{rr}
-2x + 4y = 15 \\
-12x - 4y = -8
\end{array}
\][/tex]

What value belongs in the green box?

A. [tex]\(12x\)[/tex]
B. [tex]\(3x\)[/tex]
C. [tex]\(-12x\)[/tex]
D. [tex]\(-x\)[/tex]



Answer :

Sure, let's solve the problem step by step.

We are given two equations:
1. [tex]\(-2x + 4y = 15\)[/tex],
2. [tex]\(3x + y = 2\)[/tex].

The problem asks us to multiply the second equation by [tex]\(-4\)[/tex] and determine the coefficient that would appear in place of [tex]\(3x\)[/tex] when multiplied by [tex]\(-4\)[/tex] and placed in the corresponding position in the new equation.

Let's start by writing the second equation:
[tex]\[ 3x + y = 2 \][/tex]

Step-by-step multiplication by [tex]\(-4\)[/tex]:

1. Multiply the [tex]\(3x\)[/tex] term by [tex]\(-4\)[/tex]:
[tex]\[ -4 \cdot 3x = -12x \][/tex]

2. Multiply the [tex]\(y\)[/tex] term by [tex]\(-4\)[/tex]:
[tex]\[ -4 \cdot y = -4y \][/tex]

3. Multiply the constant term [tex]\(2\)[/tex] by [tex]\(-4\)[/tex]:
[tex]\[ -4 \cdot 2 = -8 \][/tex]

Thus, after multiplying the second equation [tex]\(3x + y = 2\)[/tex] by [tex]\(-4\)[/tex], the new equation will be:
[tex]\[ -12x - 4y = -8 \][/tex]

The value that belongs in the green box is the coefficient of the [tex]\(x\)[/tex] term in this new equation, which is [tex]\(\boxed{-12}\)[/tex].