Math Problem Statement

Write the equation of the line that passes through the point (-4, -9) and has a slope of 1/2.

Solution

To find the equation of a line with a given slope and point, we use the point-slope form of a line equation:

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

where:

  • m=12m = \frac{1}{2} (the slope),
  • (x1,y1)=(4,9)(x_1, y_1) = (-4, -9) (the point the line passes through).

Step 1: Substitute the values

y(9)=12(x(4))y - (-9) = \frac{1}{2}(x - (-4))

which simplifies to:

y+9=12(x+4)y + 9 = \frac{1}{2}(x + 4)

Step 2: Distribute the slope

y+9=12x+12×4y + 9 = \frac{1}{2}x + \frac{1}{2} \times 4

y+9=12x+2y + 9 = \frac{1}{2}x + 2

Step 3: Solve for yy by isolating it on one side

y=12x+29y = \frac{1}{2}x + 2 - 9

y=12x7y = \frac{1}{2}x - 7

Answer

The equation of the line is:

y=12x7y = \frac{1}{2}x - 7

So, the correct option is:

Option C: y=12x7\text{Option C: } y = \frac{1}{2}x - 7

Would you like a detailed breakdown of each step or have any other questions?


Here are some related questions to deepen your understanding:

  1. How do you find the y-intercept of a line given a point and the slope?
  2. What is the general form of a linear equation and how does it relate to the point-slope form?
  3. How would the equation change if the slope were negative, say 12-\frac{1}{2}?
  4. How can we verify if a given point lies on a specific line?
  5. What is the difference between point-slope form and slope-intercept form?

Tip: To quickly verify your solution, substitute the given point into your final equation to see if it satisfies the equation.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form

Formulas

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

Theorems

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Suitable Grade Level

Grades 8-10