Question

Write an equation of the line that passes through the two points. $$(2,3),(-4,6)$$

Short answer

The equation of the line that passes through the points (2,3) and (-4,6) is \( y = -\frac{1}{2}x + 4 \).

Step-by-step solution

Find the slope

Using the slope formula \[m = \frac{y_2 - y_1}{x_2 - x_1}\] , use the given points to calculate the slope, m. So the slope between the points (2,3) and (-4,6) is \[m = \frac{6 - 3}{-4 - 2} = -\frac{1}{2}\].

Write equation in point-slope form

Next, use one of the points and the slope to write the equation of the line in point-slope form. Using point (2,3), the equation will be \[y - 3 = -\frac{1}{2}(x - 2)\].

Simplify the equation

Last, simplify the equation from the last step by distributing the slope throughout the parenthesis and then isolating 'y' on one side. The simplified equation is \[y = -\frac{1}{2}x + 4\].

Key concepts

Understanding the Slope Formula

Exploring the slope of a line is paramount in understanding linear equations. The slope indicates how steep a line is and the direction that it travels when graphed. If you picture a hill, a higher slope value means a steeper hill. To find the slope (\(m\)) between two points, you can use the slope formula: \( m = \frac{y_2 - y_1}{x_2 - x_1} \). In our exercise, the two points given were (2,3) and (-4,6). By subtracting the y-coordinates and the x-coordinates of these points respectively, the slope of the line is determined to be \( -\frac{1}{2} \). This result tells us that for every step you move horizontally to the right, the line falls down by half a step vertically.

In practice, making sure to subtract the coordinates in the correct order is crucial. A common mistake is switching the order and getting the wrong slope. Always remember: 'rise over run', with the 'rise' being the change in y-coordinates and the 'run' being the change in x-coordinates.

Writing Equations in Point-Slope Form

Once the slope is known, the next step in our solution process is to express the equation of the line in point-slope form. The point-slope form is expressed as \( y - y_1 = m(x - x_1) \), where \(m\) is the slope and \( (x_1, y_1) \) is a point through which the line passes. It is a direct method to write the equation of a line when you know one point on the line and its slope. From our exercise, using point (2,3) as \( (x_1, y_1) \) and the slope -1/2, the point-slope form of the equation becomes \( y - 3 = -\frac{1}{2}(x - 2) \).

Using point-slope form makes the equation relatable to a specific point, which can be extremely beneficial when dealing with graphs and plotting. Students often forget to maintain the signs inside the parenthesis, so double-checking this can prevent errors when moving forward to the next steps.

Simplifying Linear Equations

The last step is the linear equation simplification, which transforms the point-slope form into a more conventional slope-intercept form, \( y = mx + b \), where \(m\) is the slope and \(b\) is the y-intercept. Simplifying the equation involves distributing the slope \( -\frac{1}{2} \) in our case, to the \(x\) term inside the parentheses and then isolating \(y\) on one side to solve for \(b\), the y-intercept. In our example, \(y - 3 = -\frac{1}{2}(x - 2)\) distributes to \(y = -\frac{1}{2}x + 4\).

Know that simplifying the equation not only makes it easier to read but also ready for graphing. The y-intercept, \(b\), directly tells you where the line will cross the y-axis. It's essential to perform careful arithmetic during simplification to avoid sign errors that could fundamentally change the graph of the equation.