Math Problem Statement

You are asked to find an equation of a line and are given the slope and a point on the line

instead of the slope and y-intercept. What would you do differently?

Solution

When given the slope and a point on the line, instead of the slope and y-intercept, the process of finding the equation of the line involves using the point-slope form of a linear equation. Here's how you would proceed:

1. Recall the Point-Slope Form:

The point-slope form of a linear equation is given by:

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

where:

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

2. Substitute the Given Values:

  • Substitute the given slope mm into the equation.
  • Substitute the coordinates of the given point (x1,y1)(x_1, y_1) into the equation.

3. Simplify the Equation:

  • After substituting, simplify the equation to put it in either the slope-intercept form y=mx+by = mx + b or the standard form Ax+By=CAx + By = C, depending on the requirement.

Example:

Let's say you're given the slope m=3m = 3 and a point on the line (2,5)(2, -5).

  1. Start with the point-slope form: y(5)=3(x2)y - (-5) = 3(x - 2) Simplifying: y+5=3x6y + 5 = 3x - 6

  2. To put it in slope-intercept form, solve for yy: y=3x65y = 3x - 6 - 5 y=3x11y = 3x - 11

So, the equation of the line is y=3x11y = 3x - 11.

Conclusion:

The key difference is that when you have the slope and a point, you use the point-slope form to first establish the equation, and then you can convert it into the slope-intercept form or any other desired form.

Would you like to explore any more details or have other questions?

Here are some related questions that might be helpful:

  1. How do you convert an equation from point-slope form to standard form?
  2. What is the significance of the point-slope form of a line?
  3. How would you find the y-intercept after using the point-slope form?
  4. Can you determine the equation of a line if only two points are given?
  5. How would the equation change if the slope is zero?

Tip: Always double-check the point's coordinates and the slope when substituting them into the point-slope form to avoid any calculation errors.

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Math Problem Analysis

Mathematical Concepts

Linear Equations

Formulas

Point-slope form of a linear equation

Theorems

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Suitable Grade Level

Grades 7-9