Find the Line Equation Through Points (2,8) and (6,1): Coordinate Geometry

Question

Find the equation of the line passing through the two points (2,8),(6,1) (2,8),(6,1)

Video Solution

Solution Steps

00:00 Find the algebraic representation of the function
00:04 We'll use the formula to find a line equation using 2 points
00:16 In each point the left number represents X-axis and the right Y
00:30 We'll substitute the points according to the given data and find the slope
00:42 This is the line's slope
00:46 Now we'll use the line equation
00:57 We'll substitute the point according to the given data
01:03 We'll substitute the slope and solve to find the intersection point (B)
01:17 We'll isolate the intersection point (B)
01:27 This is the intersection point with the Y-axis
01:31 Now we'll substitute the intersection point and slope in the line equation
01:46 And this is the solution to the question

Step-by-Step Solution

To find the equation of the line passing through the points (2,8) (2,8) and (6,1) (6,1) , follow the steps below:

  • Step 1: Calculate the slope m m .
    The formula for the slope m m is:

m=y2y1x2x1=1862=74 m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{1 - 8}{6 - 2} = \frac{-7}{4}

  • Step 2: Use the point-slope form to write the equation of the line.
    The point-slope form of a line is given by:

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

Using the point (2,8)(2,8):

y8=74(x2) y - 8 = -\frac{7}{4}(x - 2)

  • Step 3: Simplify to the slope-intercept form.
    Distribute the slope and rearrange to find y y :

y8=74x+72 y - 8 = -\frac{7}{4}x + \frac{7}{2}

Add 8 to both sides to solve for y y :

y=74x+72+8 y = -\frac{7}{4}x + \frac{7}{2} + 8

Convert 8 to a fraction with a denominator of 2:

y=74x+72+162 y = -\frac{7}{4}x + \frac{7}{2} + \frac{16}{2}

Simplify the addition:

y=74x+232 y = -\frac{7}{4}x + \frac{23}{2}

To convert 23/2 23/2 into mixed number form: 232=1112 \frac{23}{2} = 11 \frac{1}{2}

Thus, the equation in slope-intercept form is: y=74x+1112 y = -\frac{7}{4}x + 11 \frac{1}{2}

Therefore, the equation of the line passing through these points is y=134x+1112 y = -1\frac{3}{4}x + 11\frac{1}{2} , which matches the correct choice in the multiple-choice answers.

Answer

y=134x+1112 y=-1\frac{3}{4}x+11\frac{1}{2}