Math Problem Statement

Find the y-intercept of the line which passes through (-2, -2) and (2, -4).

Solution

To find the y-intercept of the line passing through the points (2,2)(-2, -2) and (2,4)(2, -4), we can follow these steps:

Step 1: Find the slope (m)

The slope formula is:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

Using the points (2,2)(-2, -2) and (2,4)(2, -4):

m=4(2)2(2)=4+22+2=24=12m = \frac{-4 - (-2)}{2 - (-2)} = \frac{-4 + 2}{2 + 2} = \frac{-2}{4} = -\frac{1}{2}

Step 2: Use the point-slope form of a line equation

The point-slope form is:

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

Let's use the point (2,2)(-2, -2):

y(2)=12(x(2))y - (-2) = -\frac{1}{2}(x - (-2))

Simplifying:

y+2=12(x+2)y + 2 = -\frac{1}{2}(x + 2) y+2=12x1y + 2 = -\frac{1}{2}x - 1 y=12x12y = -\frac{1}{2}x - 1 - 2 y=12x3y = -\frac{1}{2}x - 3

Step 3: Find the y-intercept

The y-intercept occurs when x=0x = 0. Substituting x=0x = 0 into the equation y=12x3y = -\frac{1}{2}x - 3:

y=12(0)3=3y = -\frac{1}{2}(0) - 3 = -3

Thus, the y-intercept is (0,3)(0, -3).

Answer:

The correct choice is A. (0, -3).

Would you like more details or have any questions about this solution?

Here are 5 related questions to expand your understanding:

  1. How do you calculate the slope between two points on a line?
  2. What is the point-slope form of a line and how is it useful?
  3. How does the y-intercept relate to the equation of a line?
  4. How would the slope change if the two points were reversed?
  5. Can the y-intercept ever be the same as one of the given points?

Tip: The y-intercept is always found by setting x=0x = 0 in the equation of a line.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Coordinate Geometry

Formulas

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

Theorems

Slope formula theorem
Line equation theorem

Suitable Grade Level

Grades 8-10