Q. Which Graph Represents \( y – 1 = 2(x – 2) \)?
Answer
- Expand the equation.
Distribute the 2 on the right side.
\[ y – 1 = 2x – 4 \]
- Convert to slope-intercept form.
Add 1 to both sides.
\[ y = 2x – 3 \]
- Identify the features for the graph.
The line has a slope of 2 and passes through the y-intercept (0, -3) and the given point (2, 1).
Detailed Explanation
Problem
Which graph represents the line given by the equation
\( y – 1 = 2(x – 2) \)
Step-by-step detailed solution
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Expand and rewrite into slope-intercept form
Start with the given point-slope form:
\( y – 1 = 2(x – 2) \)
First distribute the 2 on the right-hand side:
\( y – 1 = 2x – 4 \)
Next isolate \( y \) by adding 1 to both sides:
\( y = 2x – 4 + 1 \)
Combine like terms on the right-hand side:
\( y = 2x – 3 \)
This is the slope-intercept form \( y = mx + b \) with slope \( m = 2 \) and y-intercept \( b = -3 \).
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Interpret slope and intercept
The slope \( m = 2 \) means that for each increase of 1 in \( x \), \( y \) increases by 2. The y-intercept \( b = -3 \) means the line crosses the y-axis at the point \( (0,-3) \).
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Generate points to plot the line
Choose a few x-values, compute y using \( y = 2x – 3 \), and list the corresponding points:
\(x\) \(y = 2x – 3\) Point 0 \(2(0) – 3 = -3\) \((0,-3)\) 1 \(2(1) – 3 = -1\) \((1,-1)\) 2 \(2(2) – 3 = 1\) \((2,1)\) \(\tfrac{3}{2}\) \(2\left(\tfrac{3}{2}\right) – 3 = 0\) \(\left(\tfrac{3}{2},0\right)\) (x-intercept) These points lie on the line and are sufficient to draw it accurately.
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Describe the graph
The graph is a straight line that:
- passes through \( (0,-3) \) (y-intercept),
- passes through \( (2,1) \) (the point given implicitly by the original point-slope form),
- rises to the right because the slope is positive, and for every 1 unit increase in \( x \), \( y \) increases by 2, so the line is fairly steep upward.
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Final identification
The correct graph is the straight line with equation
\( y = 2x – 3 \)
So pick the graph that shows a line with slope 2 and y-intercept at \( (0,-3) \).
Graph
Frequently Asked Questions
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What is the slope and y-intercept of this line?
Which point does the equation guarantee the line passes through?
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What is the x-intercept of the line?
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How steep is the line; what does slope 2 mean geometrically?
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