Finding the Slope of the Line

Oct 13, 2025 by wbrum.org 66 views

Introduction

The point-slope equation of a line is a mathematical formula used to find the equation of a line given two points on the line. In this article, we will learn how to complete the point-slope equation of a line through two given points, ${(-5,7)}$ and ${(-4,0)}$ . We will use exact numbers and follow the point-slope formula to find the equation of the line.

Understanding the Point-Slope Formula

The point-slope formula is given by:

${ y - y_1 = m(x - x_1) }$

where ${(x_1, y_1)}$ is a point on the line and ${m}$ is the slope of the line. The slope of the line can be found using the formula:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

where ${(x_2, y_2)}$ is another point on the line.

Finding the Slope of the Line

To find the slope of the line, we will use the two given points, ${(-5,7)}$ and ${(-4,0)}$ . We will substitute these values into the slope formula:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

${ m = \frac{0 - 7}{-4 - (-5)} }$

${ m = \frac{-7}{1} }$

${ m = -7 }$

So, the slope of the line is ${-7}$ .

Completing the Point-Slope Equation

Now that we have the slope of the line, we can substitute it into the point-slope formula:

${ y - y_1 = m(x - x_1) }$

We will use the point ${(-5,7)}$ as ${(x_1, y_1)}$ and substitute the slope ${m = -7}$ :

${ y - 7 = -7(x - (-5)) }$

${ y - 7 = -7(x + 5) }$

${ y - 7 = -7x - 35 }$

Now, we can simplify the equation by adding ${7}$ to both sides:

${ y = -7x - 28 }$

So, the point-slope equation of the line through the points ${(-5,7)}$ and ${(-4,0)}$ is:

${ y = -7x - 28 }$

Conclusion

In this article, we learned how to complete the point-slope equation of a line through two given points. We used the point-slope formula and found the slope of the line using the two given points. We then substituted the slope into the point-slope formula and simplified the equation to find the final answer. The point-slope equation of the line through the points ${(-5,7)}$ and ${(-4,0)}$ is:

${ y = -7x - 28 }$

Example Problems

Find the point-slope equation of the line through the points ${(2,3)}$ and ${(4,5)}$ .
Find the point-slope equation of the line through the points ${(-2,4)}$ and ${(-1,6)}$ .

Solutions

To find the point-slope equation of the line through the points ${(2,3)}$ and ${(4,5)}$ , we will first find the slope of the line using the two given points:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

${ m = \frac{5 - 3}{4 - 2} }$

${ m = \frac{2}{2} }$

${ m = 1 }$

Now, we can substitute the slope into the point-slope formula:

${ y - y_1 = m(x - x_1) }$

We will use the point ${(2,3)}$ as ${(x_1, y_1)}$ and substitute the slope ${m = 1}$ :

${ y - 3 = 1(x - 2) }$

${ y - 3 = x - 2 }$

Now, we can simplify the equation by adding ${3}$ to both sides:

${ y = x + 1 }$

So, the point-slope equation of the line through the points ${(2,3)}$ and ${(4,5)}$ is:

${ y = x + 1 }$

To find the point-slope equation of the line through the points ${(-2,4)}$ and ${(-1,6)}$ , we will first find the slope of the line using the two given points:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

${ m = \frac{6 - 4}{-1 - (-2)} }$

${ m = \frac{2}{1} }$

${ m = 2 }$

Now, we can substitute the slope into the point-slope formula:

${ y - y_1 = m(x - x_1) }$

We will use the point ${(-2,4)}$ as ${(x_1, y_1)}$ and substitute the slope ${m = 2}$ :

${ y - 4 = 2(x - (-2)) }$

${ y - 4 = 2(x + 2) }$

${ y - 4 = 2x + 4 }$

Now, we can simplify the equation by adding ${4}$ to both sides:

${ y = 2x + 8 }$

So, the point-slope equation of the line through the points ${(-2,4)}$ and ${(-1,6)}$ is:

${ y = 2x + 8 }$

Final Answer

The point-slope equation of the line through the points ${(-5,7)}$ and ${(-4,0)}$ is:

Frequently Asked Questions

Q: What is the point-slope equation of a line?

A: The point-slope equation of a line is a mathematical formula used to find the equation of a line given two points on the line. It is given by:

${ y - y_1 = m(x - x_1) }$

where ${(x_1, y_1)}$ is a point on the line and ${m}$ is the slope of the line.

Q: How do I find the slope of the line using the point-slope equation?

A: To find the slope of the line, you can use the formula:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

where ${(x_2, y_2)}$ is another point on the line.

Q: What if I have two points on the line, but I don't know the slope?

A: If you have two points on the line, you can use the point-slope equation to find the slope. First, find the slope using the formula:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

Then, substitute the slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Q: Can I use the point-slope equation to find the equation of a line if I only have one point?

A: No, you cannot use the point-slope equation to find the equation of a line if you only have one point. You need at least two points to find the slope of the line.

Q: How do I simplify the point-slope equation?

A: To simplify the point-slope equation, you can add or subtract the same value to both sides of the equation. For example, if you have:

${ y - 3 = 2(x - 2) }$

You can add 3 to both sides to get:

${ y = 2x - 1 }$

Q: Can I use the point-slope equation to find the equation of a horizontal line?

A: Yes, you can use the point-slope equation to find the equation of a horizontal line. A horizontal line has a slope of 0, so the point-slope equation becomes:

${ y - y_1 = 0(x - x_1) }$

${ y - y_1 = 0 }$

Q: Can I use the point-slope equation to find the equation of a vertical line?

A: Yes, you can use the point-slope equation to find the equation of a vertical line. A vertical line has an undefined slope, so the point-slope equation becomes:

${ y - y_1 = \infty(x - x_1) }$

However, this is not a valid equation, so you need to use a different method to find the equation of a vertical line.

Q: What if I have a point on the line and the slope, but I don't know the equation of the line?

A: If you have a point on the line and the slope, you can use the point-slope equation to find the equation of the line. First, substitute the point and slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Then, simplify the equation to find the final answer.

Q: Can I use the point-slope equation to find the equation of a line if I have a point on the line and the equation of a parallel line?

A: No, you cannot use the point-slope equation to find the equation of a line if you have a point on the line and the equation of a parallel line. You need to use a different method to find the equation of a line.

Q: What if I have a point on the line and the equation of a perpendicular line?

A: If you have a point on the line and the equation of a perpendicular line, you can use the point-slope equation to find the equation of the line. First, find the slope of the perpendicular line using the formula:

${ m = -\frac{1}{m} }$

where ${m}$ is the slope of the original line. Then, substitute the point and slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Then, simplify the equation to find the final answer.

Q: Can I use the point-slope equation to find the equation of a line if I have a point on the line and the equation of a line that passes through the same point?

A: No, you cannot use the point-slope equation to find the equation of a line if you have a point on the line and the equation of a line that passes through the same point. You need to use a different method to find the equation of a line.

Q: What if I have a point on the line and the equation of a line that is a tangent to the original line?

A: If you have a point on the line and the equation of a line that is a tangent to the original line, you can use the point-slope equation to find the equation of the line. First, find the slope of the tangent line using the formula:

${ m = \frac{dy}{dx} }$

where ${\frac{dy}{dx}}$ is the derivative of the original line. Then, substitute the point and slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Then, simplify the equation to find the final answer.

Q: Can I use the point-slope equation to find the equation of a line if I have a point on the line and the equation of a line that is a secant to the original line?

A: No, you cannot use the point-slope equation to find the equation of a line if you have a point on the line and the equation of a line that is a secant to the original line. You need to use a different method to find the equation of a line.

Q: What if I have a point on the line and the equation of a line that is a chord to the original line?

A: If you have a point on the line and the equation of a line that is a chord to the original line, you can use the point-slope equation to find the equation of the line. First, find the slope of the chord line using the formula:

${ m = \frac{y_2 - y_1}{x_2 - x_1} }$

where ${(x_2, y_2)}$ is another point on the chord line. Then, substitute the point and slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Then, simplify the equation to find the final answer.

Q: Can I use the point-slope equation to find the equation of a line if I have a point on the line and the equation of a line that is a circle?

A: No, you cannot use the point-slope equation to find the equation of a line if you have a point on the line and the equation of a line that is a circle. You need to use a different method to find the equation of a line.

Q: What if I have a point on the line and the equation of a line that is a parabola?

A: If you have a point on the line and the equation of a line that is a parabola, you can use the point-slope equation to find the equation of the line. First, find the slope of the parabola using the formula:

${ m = \frac{dy}{dx} }$

where ${\frac{dy}{dx}}$ is the derivative of the parabola. Then, substitute the point and slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Then, simplify the equation to find the final answer.

Q: Can I use the point-slope equation to find the equation of a line if I have a point on the line and the equation of a line that is a hyperbola?

A: No, you cannot use the point-slope equation to find the equation of a line if you have a point on the line and the equation of a line that is a hyperbola. You need to use a different method to find the equation of a line.

Q: What if I have a point on the line and the equation of a line that is an ellipse?

A: If you have a point on the line and the equation of a line that is an ellipse, you can use the point-slope equation to find the equation of the line. First, find the slope of the ellipse using the formula:

${ m = \frac{dy}{dx} }$

where ${\frac{dy}{dx}}$ is the derivative of the ellipse. Then, substitute the point and slope into the point-slope equation:

${ y - y_1 = m(x - x_1) }$

Then, simplify the equation to find the final answer.