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If the point (4, -2) is included in a direct variation relationship, which point also belongs in this direct variation?

A. (-4, 2)
B. (-4, -2)
C. (2, -4)
D. (-2, 4)


Sagot :

To determine which point also belongs to the direct variation relationship that includes the point [tex]\((4, -2)\)[/tex], we can follow these steps:

1. Understand Direct Variation:
Direct variation means that [tex]\( y \)[/tex] varies directly as [tex]\( x \)[/tex]. This can be expressed with the equation [tex]\( y = kx \)[/tex], where [tex]\( k \)[/tex] is a constant.

2. Find the Constant [tex]\( k \)[/tex]:
Given the point [tex]\((4, -2)\)[/tex], we plug in [tex]\( x = 4 \)[/tex] and [tex]\( y = -2 \)[/tex] into the equation [tex]\( y = kx \)[/tex]:
[tex]\[ -2 = k \cdot 4 \][/tex]
Solving for [tex]\( k \)[/tex]:
[tex]\[ k = \frac{-2}{4} = -0.5 \][/tex]

3. Determine if Each Point Satisfies the Equation:
We need to check if the given points satisfy the equation [tex]\( y = -0.5x \)[/tex].

- Option A: [tex]\((-4, 2)\)[/tex]
[tex]\[ y = -0.5 \cdot (-4) = 2 \][/tex]
The point [tex]\((-4, 2)\)[/tex] satisfies [tex]\( y = -0.5x \)[/tex].

- Option B: [tex]\((-4, -2)\)[/tex]
[tex]\[ y = -0.5 \cdot (-4) = 2 \quad \text{(not } y = -2 \text{)} \][/tex]
The point [tex]\((-4, -2)\)[/tex] does not satisfy [tex]\( y = -0.5x \)[/tex].

- Option C: [tex]\((2, -4)\)[/tex]
[tex]\[ y = -0.5 \cdot 2 = -1 \quad \text{(not } y = -4 \text{)} \][/tex]
The point [tex]\((2, -4)\)[/tex] does not satisfy [tex]\( y = -0.5x \)[/tex].

- Option D: [tex]\((-2, 4)\)[/tex]
[tex]\[ y = -0.5 \cdot (-2) = 1 \quad \text{(not } y = 4 \text{)} \][/tex]
The point [tex]\((-2, 4)\)[/tex] does not satisfy [tex]\( y = -0.5x \)[/tex].

Based on our checks, only [tex]\((-4, 2)\)[/tex] satisfies the direct variation relationship [tex]\( y = -0.5x \)[/tex] established by the point [tex]\((4, -2)\)[/tex].

The correct answer is:
[tex]\[ \boxed{A} \][/tex]