Math Problem Statement

Question

Which is an equation in point-slope form for the line that passes through the points (−1,4)(−1,4) and (3,−4)(3,−4)?

Solution

To find the equation of a line in point-slope form, we follow these steps:

Step 1: Find the slope mm

The formula to calculate the slope between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

Substitute the given points (1,4)(-1, 4) and (3,4)(3, -4) into the formula:

m=443(1)=83+1=84=2m = \frac{-4 - 4}{3 - (-1)} = \frac{-8}{3 + 1} = \frac{-8}{4} = -2

Step 2: Use the point-slope form equation

The point-slope form of a line's equation is:

yy1=m(xx1)y - y_1 = m(x - x_1)

We can use either of the given points. Let's use (1,4)(-1, 4):

y4=2(x(1))=2(x+1)y - 4 = -2(x - (-1)) = -2(x + 1)

Step 3: Simplify (optional)

We could leave it as is, or distribute to simplify:

y4=2x2y - 4 = -2x - 2 y=2x+2y = -2x + 2

So, the equation in point-slope form is:

y4=2(x+1)y - 4 = -2(x + 1)

Do you want more details or have any questions about this?


Here are 5 related questions you can try:

  1. How do you convert the point-slope form to slope-intercept form?
  2. What is the general form of the equation of a line?
  3. How do you find the equation of a line if you're given the slope and one point?
  4. What happens to the point-slope form if the slope is zero?
  5. How can you find the midpoint between two points?

Tip: Point-slope form is very useful when you know the slope and one point on the line!

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Point-Slope Form

Formulas

Slope formula m = (y2 - y1) / (x2 - x1)
Point-slope form y - y1 = m(x - x1)

Theorems

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Suitable Grade Level

Grades 8-10