Math Problem Statement

A line has a slope of –3 and passes through the point (–7,1). Write its equation in slope-intercept form.

Solution

To find the equation of the line in slope-intercept form (y=mx+by = mx + b), we are given:

  • Slope (mm): 3-3
  • Point (x1,y1x_1, y_1): (7,1)(-7, 1)

Step 1: Use the Point-Slope Formula

The point-slope formula is: yy1=m(xx1)y - y_1 = m(x - x_1)

Step 2: Plug in the Given Values

y1=3(x+7)y - 1 = -3(x + 7)

Step 3: Expand the Equation

Distribute the 3-3: y1=3x21y - 1 = -3x - 21

Step 4: Isolate yy

y=3x20y = -3x - 20

Final Answer

The equation of the line in slope-intercept form is: y=3x20y = -3x - 20

Would you like more details on how this was derived, or do you have any questions?

Related Questions:

  1. How do you find the slope given two points on a line?
  2. How do you convert a line from point-slope to standard form?
  3. What does the y-intercept (bb) represent in a real-world context?
  4. How do you verify that a point lies on a given line?
  5. Can a line with a slope of zero be expressed in slope-intercept form?

Tip:

To quickly write the equation of a line, remember the point-slope form and understand how to isolate yy to achieve the slope-intercept form.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form

Formulas

Point-Slope Form: y - y1 = m(x - x1)
Slope-Intercept Form: y = mx + b

Theorems

Point-Slope Formula
Slope-Intercept Form Transformation

Suitable Grade Level

Grades 8-10