Math Problem Statement

Write in slope-intercept form an equation of the line that passes through the given points. (-1, 7), (3, -1)

Solution

Let's solve the problem step by step.

The goal is to find the equation of the line in slope-intercept form, y=mx+by = mx + b, using the two points (1,7)(-1, 7) and (3,1)(3, -1).


Step 1: Find the slope (mm)

The formula for 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 (1,7)(-1, 7) and (3,1)(3, -1):

m=173(1)=83+1=84=2m = \frac{-1 - 7}{3 - (-1)} = \frac{-8}{3 + 1} = \frac{-8}{4} = -2

So, the slope is m=2m = -2.


Step 2: Find the yy-intercept (bb)

Using the slope-intercept form equation, y=mx+by = mx + b, we can substitute one of the points (e.g., (1,7)(-1, 7)) and the slope m=2m = -2 to solve for bb:

y=mx+by = mx + b

Substitute y=7y = 7, x=1x = -1, and m=2m = -2:

7=2(1)+b7 = -2(-1) + b

7=2+b7 = 2 + b

b=72=5b = 7 - 2 = 5

So, the yy-intercept is b=5b = 5.


Step 3: Write the equation

Now that we know m=2m = -2 and b=5b = 5, the equation of the line is:

y=2x+5y = -2x + 5


Final Answer:

y=2x+5y = -2x + 5


Would you like further explanation or details? Here are 5 related questions to expand your understanding:

  1. How can you verify if the equation y=2x+5y = -2x + 5 passes through both points?
  2. What is the general formula for slope-intercept form, and how does it relate to the point-slope formula?
  3. What happens to the equation if the slope is 00 or undefined?
  4. How would the equation look in standard form instead of slope-intercept form?
  5. What is the significance of the yy-intercept in a real-world context?

Tip: Always double-check your slope calculation by ensuring that the denominator (change in xx) is not zero to avoid undefined slopes.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Slope-intercept form: y = mx + b

Theorems

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Suitable Grade Level

Grades 7-9