Math Problem Statement

Find an equation of the line that passes through the two given points. Write the equation in slope-intercept form, if possible. See Example 2.

passes through (−2, 2) and (2, −8)    

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Solution

To find the equation of the line that passes through two points, we follow these steps:

  1. Find the slope using the formula: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1} where (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) are the coordinates of the two points.

  2. Use the point-slope form of a line equation: yy1=m(xx1)y - y_1 = m(x - x_1) and convert it to the slope-intercept form y=mx+by = mx + b.

Step 1: Calculate the slope mm

We have the points (2,2)(-2, 2) and (2,8)(2, -8).

m=822(2)=104=52m = \frac{-8 - 2}{2 - (-2)} = \frac{-10}{4} = -\frac{5}{2}

Step 2: Use point-slope form

We can choose one of the points, say (2,2)(-2, 2), to substitute into the point-slope form.

y2=52(x(2))y - 2 = -\frac{5}{2}(x - (-2))

Simplify the equation:

y2=52(x+2)y - 2 = -\frac{5}{2}(x + 2) y2=52x5y - 2 = -\frac{5}{2}x - 5 y=52x5+2y = -\frac{5}{2}x - 5 + 2 y=52x3y = -\frac{5}{2}x - 3

Final Answer:

The equation of the line in slope-intercept form is: y=52x3y = -\frac{5}{2}x - 3

Would you like further details or have any questions?

Related Questions:

  1. How do you derive the equation of a line from its slope and a point on the line?
  2. What is the significance of the slope in the slope-intercept form?
  3. How do you convert point-slope form to slope-intercept form?
  4. What are the steps to graph a line given its equation in slope-intercept form?
  5. How can you check if a point lies on a given line?

Tip:

When calculating the slope, always be careful with the signs of the coordinates to avoid mistakes in the equation.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form

Formulas

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

Theorems

Concept of slope
Linear equation derivation

Suitable Grade Level

Grades 8-10