QUESTION IMAGE
Question
all and sid graphed this system:
$y = -\frac{1}{4}x - 1$
$y = \frac{1}{4}x - 3$
they marked its solutions with points p and r.
which statement describes ali and sid’s solutions?
\bigcirc their solutions are correct.
\bigcirc they marked the y-intercepts instead of the intersection point of the two lines.
\bigcirc they marked the y-intercepts instead of the x-intercepts.
\bigcirc they marked only the x-intercepts instead of the x - and y-intercepts.
To determine the error in Ali and Sid's solutions, we analyze the system of equations \( y = -\frac{1}{4}x - 1 \) and \( y=\frac{1}{4}x - 3 \). The solution to a system of linear equations is the intersection point of the two lines. Let's find the intercepts and the intersection:
- Find \( y \)-intercepts:
- For \( y = -\frac{1}{4}x - 1 \), when \( x = 0 \), \( y=-1 \).
- For \( y=\frac{1}{4}x - 3 \), when \( x = 0 \), \( y = - 3 \). Wait, but looking at the graph, point \( P \) is at \( (0, - 1) \)? Wait, no, maybe I misread. Wait, the options suggest they marked \( y \)-intercepts instead of the intersection. Let's find the intersection:
Set \( -\frac{1}{4}x - 1=\frac{1}{4}x - 3 \)
\( -\frac{1}{4}x-\frac{1}{4}x=-3 + 1 \)
\( -\frac{2}{4}x=-2 \)
\( -\frac{1}{2}x=-2 \)
\( x = 4 \)
Then \( y=-\frac{1}{4}(4)-1=-1 - 1=-2 \)? Wait, maybe my calculation is wrong. Wait, let's re - solve:
\( -\frac{1}{4}x - 1=\frac{1}{4}x - 3 \)
Add \( \frac{1}{4}x \) to both sides: \( - 1=\frac{2}{4}x-3 \)
Add 3 to both sides: \( 2=\frac{1}{2}x \)
Multiply both sides by 2: \( x = 4 \)
Then \( y=\frac{1}{4}(4)-3=1 - 3=-2 \). So the intersection point is \( (4,-2) \).
Now, point \( P \): Let's check the coordinates of \( P \). From the graph, \( P \) seems to be on the \( x \)-axis? Wait, no, the options are about intercepts. Let's check the \( y \)-intercepts:
- For \( y = -\frac{1}{4}x - 1 \), \( y \)-intercept is \( (0,-1) \)
- For \( y=\frac{1}{4}x - 3 \), \( y \)-intercept is \( (0,-3) \)
But the points marked are \( P \) and \( R \). If \( P \) is \( (0, - 1) \) (the \( y \)-intercept of the first line) and \( R \) is \( (-4,0) \) (the \( x \)-intercept of the first line: \( 0=-\frac{1}{4}x - 1\Rightarrow x=-4 \))? Wait, the option "They marked the \( y \)-intercepts instead of the intersection" or "They marked \( y \)-intercepts instead of \( x \)-intercepts"? Wait, the options are:
- Their solutions are correct. No, because the solution is the intersection, not the intercepts.
- They marked the intersection point of the two lines. No, because the intercepts are not the intersection.
- They marked the \( y \)-intercepts instead of the \( x \)-intercepts. No, let's re - evaluate.
Wait, the correct approach: The solution to the system is the intersection of the two lines. If they marked points \( P \) and \( R \), which are likely the \( y \)-intercept (for one line) and \( x \)-intercept (for the other), but the key is that the solution of the system is the intersection, not the intercepts. So the statement "They marked the \( y \)-intercepts instead of the intersection" is correct? Wait, the options given:
Option 1: Their solutions are correct. No.
Option 2: They marked the \( y \)-intercepts instead of the intersection. Yes, because the solution is the intersection, not the \( y \)-intercepts.
Option 3: They marked the \( y \)-intercepts instead of the \( x \)-intercepts. No.
Option 4: They marked only the \( x \)-intercepts instead of the \( y \)-intercepts. No.
So the correct statement is "They marked the \( y \)-intercepts instead of the intersection point of the two lines." But looking at the options, the closest is "They marked the \( y \)-intercepts instead of the intersection" (the second option in the list: "They marked the \( y \)-intercepts instead of the intersection, point of the two lines." Wait, the original options:
The options are:
- Their solutions are correct.
- They marked the \( y \)-intercepts instead of the intersection, point of the…
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They marked the \( y \)-intercepts instead of the intersection, point of the two lines. (The second option in the given choices)