Example

Finding the Equation of a Line Through (5,4)(5, 4) and (3,6)(3, 6)

To find the equation of a line containing the points (5,4)(5, 4) and (3,6)(3, 6), apply the four-step two-points procedure and write the result in slope-intercept form.

Step 1 — Find the slope using the given points. Apply the slope formula with (x1,y1)=(5,4)(x_1, y_1) = (5, 4) and (x2,y2)=(3,6)(x_2, y_2) = (3, 6):

m=y2y1x2x1=6435=22=1m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{6 - 4}{3 - 5} = \frac{2}{-2} = -1

Step 2 — Choose one point. Use (5,4)(5, 4), so x1=5x_1 = 5 and y1=4y_1 = 4.

Step 3 — Substitute into the point-slope form yy1=m(xx1)y - y_1 = m(x - x_1):

y4=1(x5)y - 4 = -1(x - 5)

Distribute on the right side:

y4=x+5y - 4 = -x + 5

Step 4 — Write in slope-intercept form by adding 4 to both sides:

y=x+9y = -x + 9

The equation of the line is y=x+9y = -x + 9. Using the other point (3,6)(3, 6) in Step 2 produces the same final equation, confirming that either point may be chosen.

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Updated 2026-04-21

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