A line passes through (2, 2) and is perpendicular to the line 3x + y = 3. Its y-intercept is
4/3
The question asks us to find the y-intercept of a specific line. We are given two key pieces of information about this line:
To find the y-intercept, we first need to determine the equation of the required line. We can do this by finding its slope and using the given point.
The given line has the equation \(3x + y = 3\). To find its slope, we can rewrite this equation in the slope-intercept form, which is \(y = mx + c\), where \(m\) is the slope and \(c\) is the y-intercept.
Rearranging the equation \(3x + y = 3\):
Subtract \(3x\) from both sides:
\(y = -3x + 3\)
Comparing this to \(y = mx + c\), we can see that the slope of the given line is \(m_1 = -3\).
We are told that the required line is perpendicular to the line \(3x + y = 3\). For two non-vertical lines to be perpendicular, the product of their slopes must be -1.
Let \(m_2\) be the slope of the required line. Then, we have:
\(m_1 \times m_2 = -1\)
Substituting the value of \(m_1\):
\(-3 \times m_2 = -1\)
To find \(m_2\), divide both sides by -3:
\(m_2 = \frac{-1}{-3} = \frac{1}{3}\)
So, the slope of the required line is \(\frac{1}{3}\).
We know the required line passes through the point \((x_1, y_1) = (2, 2)\) and has a slope \(m = \frac{1}{3}\). We can use the point-slope form of a linear equation, which is \(y - y_1 = m(x - x_1)\).
Substitute the known values into the point-slope form:
\(y - 2 = \frac{1}{3}(x - 2)\)
Now, we can simplify this equation to get it into slope-intercept form \(y = mx + c\):
\(y - 2 = \frac{1}{3}x - \frac{1}{3}(2)\)
\(y - 2 = \frac{1}{3}x - \frac{2}{3}\)
Add 2 to both sides of the equation:
\(y = \frac{1}{3}x - \frac{2}{3} + 2\)
To add \(- \frac{2}{3}\) and 2, we need a common denominator:
\(y = \frac{1}{3}x - \frac{2}{3} + \frac{6}{3}\)
\(y = \frac{1}{3}x + \frac{4}{3}\)
This is the equation of the required line in the form \(y = mx + c\).
In the slope-intercept form of a linear equation, \(y = mx + c\), the constant term \(c\) represents the y-intercept. The y-intercept is the point where the line crosses the y-axis, which occurs when \(x = 0\).
From the equation we found, \(y = \frac{1}{3}x + \frac{4}{3}\), the constant term is \(\frac{4}{3}\).
Alternatively, set \(x = 0\) in the equation:
\(y = \frac{1}{3}(0) + \frac{4}{3}\)
\(y = 0 + \frac{4}{3}\)
\(y = \frac{4}{3}\)
The y-intercept is \(\frac{4}{3}\).
The y-intercept of the line that passes through (2, 2) and is perpendicular to the line \(3x + y = 3\) is \(\frac{4}{3}\). This corresponds to one of the given options.
| Concept | Description | Formula/Example |
|---|---|---|
| Slope-Intercept Form | A way to write linear equations (\(y = mx + c\)) where \(m\) is the slope and \(c\) is the y-intercept. | \(y = 2x + 5\) (Slope = 2, Y-intercept = 5) |
| Slope of a Line | A measure of the steepness of a line (\(m = \frac{\Delta y}{\Delta x}\)). | Line \(y = -3x + 3\) has slope \(m = -3\). |
| Perpendicular Lines | Two lines that intersect at a 90-degree angle. Their slopes (\(m_1, m_2\)) have a product of -1 (\(m_1 m_2 = -1\)), provided neither line is vertical. | If \(m_1 = 2\), then \(m_2 = -\frac{1}{2}\) for a perpendicular line. |
| Point-Slope Form | A way to write linear equations using a point \((x_1, y_1)\) the line passes through and its slope \(m\). | \(y - y_1 = m(x - x_1)\) |
| Y-intercept | The point where the line crosses the y-axis. The x-coordinate is always 0. | For \(y = \frac{1}{3}x + \frac{4}{3}\), the y-intercept is \(\frac{4}{3}\), occurring at the point \((0, \frac{4}{3})\). |
Coordinate geometry is a branch of mathematics that uses coordinates to study geometric shapes and figures. Understanding the relationships between lines, points, and slopes is fundamental.
Finding the equation of a line is a common task in coordinate geometry. The method used depends on the information given (e.g., two points, a point and a slope, slope and y-intercept).
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