Math Problem Statement

Write an equation for line L in point-slope form and slope-intercept form. Line L is parallel to y = 3x and passes through the point (1, -2).

Solution

The problem asks for the equation of line LL, which is parallel to the line y=3xy = 3x and passes through the point (1,2)(1, -2). We are required to express this equation in both point-slope form and slope-intercept form.

1. Point-Slope Form:

The point-slope form of a line is given by:

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

where (x1,y1)(x_1, y_1) is a point on the line and mm is the slope.

  • Since line LL is parallel to y=3xy = 3x, it has the same slope, which is m=3m = 3.
  • The given point on the line is (1,2)(1, -2).

Substituting these values into the point-slope form:

y(2)=3(x1)y - (-2) = 3(x - 1)

Simplifying:

y+2=3(x1)y + 2 = 3(x - 1)

This is the equation of line LL in point-slope form.

2. Slope-Intercept Form:

To convert this to slope-intercept form, we'll expand and simplify the equation. Start from the point-slope form:

y+2=3(x1)y + 2 = 3(x - 1)

First, distribute the 3 on the right-hand side:

y+2=3x3y + 2 = 3x - 3

Now subtract 2 from both sides:

y=3x32y = 3x - 3 - 2

Simplifying:

y=3x5y = 3x - 5

Thus, the equation of line LL in slope-intercept form is:

y=3x5y = 3x - 5

Final Answer:

  • Point-slope form: y+2=3(x1)y + 2 = 3(x - 1)
  • Slope-intercept form: y=3x5y = 3x - 5

Would you like further details on the process or clarification on any step?

Here are some related questions to deepen your understanding:

  1. What is the relationship between slopes of parallel lines?
  2. How would the equation change if the line were perpendicular to y=3xy = 3x?
  3. Can you derive the equation of a line if only two points are given instead of a point and a slope?
  4. How does the slope-intercept form help in graphing a line?
  5. What is the general method for converting from point-slope form to slope-intercept form?

Tip: When dealing with parallel lines, remember that they always have the same slope!

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope
Parallel Lines

Formulas

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

Theorems

Parallel lines have the same slope.

Suitable Grade Level

Grades 8-10