Math Problem Statement

Find the equation of the line. Write your answer as exact expression with fractions if necessary.

a) through (-5,2) and (4,1)

y=   

b) through (-5,2) parallel to y=-3x+6

y=   

c) through (-5,2) perpendicular to y=-1x-1

y=   

Solution

Let's solve each of these questions step by step.


a) Through points (-5, 2) and (4, 1)

The equation of a line can be written in slope-intercept form:
y=mx+by = mx + b where mm is the slope, and bb is the y-intercept.

Step 1: Find the slope (m)

The slope mm between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is given by: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1} Substituting the points (5,2)(-5, 2) and (4,1)(4, 1): m=124(5)=14+5=19m = \frac{1 - 2}{4 - (-5)} = \frac{-1}{4 + 5} = \frac{-1}{9}

So, the slope m=19m = -\frac{1}{9}.

Step 2: Use point-slope form to find the equation

Now, we use the point-slope form of the equation of a line: yy1=m(xx1)y - y_1 = m(x - x_1) Substitute m=19m = -\frac{1}{9} and the point (5,2)(-5, 2): y2=19(x+5)y - 2 = -\frac{1}{9}(x + 5) Now simplify: y2=19x59y - 2 = -\frac{1}{9}x - \frac{5}{9} y=19x59+2y = -\frac{1}{9}x - \frac{5}{9} + 2 Convert 2 to a fraction with denominator 9: y=19x59+189y = -\frac{1}{9}x - \frac{5}{9} + \frac{18}{9} y=19x+139y = -\frac{1}{9}x + \frac{13}{9}

Thus, the equation is: y=19x+139y = -\frac{1}{9}x + \frac{13}{9}


b) Through (-5, 2) parallel to y=3x+6y = -3x + 6

Step 1: Identify the slope

Since the line we are looking for is parallel to y=3x+6y = -3x + 6, the slope will be the same as the slope of this line. The slope of y=3x+6y = -3x + 6 is m=3m = -3.

Step 2: Use point-slope form

Using the point-slope form with slope m=3m = -3 and the point (5,2)(-5, 2): y2=3(x+5)y - 2 = -3(x + 5) Simplify: y2=3x15y - 2 = -3x - 15 y=3x15+2y = -3x - 15 + 2 y=3x13y = -3x - 13

Thus, the equation is: y=3x13y = -3x - 13


c) Through (-5, 2) perpendicular to y=x1y = -x - 1

Step 1: Identify the slope

The slope of y=x1y = -x - 1 is m=1m = -1. For a line to be perpendicular, the slope must be the negative reciprocal of 1-1, which is 11.

Step 2: Use point-slope form

Using the point-slope form with slope m=1m = 1 and the point (5,2)(-5, 2): y2=1(x+5)y - 2 = 1(x + 5) Simplify: y2=x+5y - 2 = x + 5 y=x+5+2y = x + 5 + 2 y=x+7y = x + 7

Thus, the equation is: y=x+7y = x + 7


Let me know if you need more details or clarifications.

Here are 5 related questions:

  1. What is the equation of a line passing through (3, 4) and (5, -2)?
  2. Find the slope of a line parallel to y=2x+1y = 2x + 1.
  3. What is the equation of a line perpendicular to y=4x3y = 4x - 3 through point (1, 5)?
  4. How do you find the y-intercept of a line given two points?
  5. What does it mean geometrically for two lines to be parallel or perpendicular?

Tip: When finding the equation of a line from two points, always start by finding the slope, then use the point-slope form for simplicity.

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form
Point-Slope Form
Parallel and Perpendicular Lines

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Slope-intercept form: y = mx + b
Point-slope form: y - y1 = m(x - x1)
Negative reciprocal for perpendicular slopes: m1 * m2 = -1

Theorems

Properties of parallel and perpendicular lines

Suitable Grade Level

Grades 8-10