Example

Finding the Equation of a Line Perpendicular to y=2x3y = 2x - 3 Through (2,1)(-2, 1)

To calculate the equation of a line perpendicular to y=2x3y = 2x - 3 that intersects the coordinate plane at the point (2,1)(-2, 1), follow the five-step procedure for perpendicular lines. Step 1 — Find the original slope. The given equation is y=2x3y = 2x - 3. Because it is provided in slope-intercept form, the slope is readily apparent: m=2m = 2. Step 2 — Determine the perpendicular slope. Perpendicular lines meet at right angles and therefore have negative reciprocal slopes. Taking the opposite reciprocal of 22 dictates that the new slope is m=12m_{\perp} = -\frac{1}{2}. Step 3 — Identify the specific point. The perpendicular line is required to pass through (x1,y1)=(2,1)(x_1, y_1) = (-2, 1). Step 4 — Substitute these values into the point-slope form. Use the equation template yy1=m(xx1)y - y_1 = m(x - x_1): y1=12(x(2))y - 1 = -\frac{1}{2}(x - (-2)) Simplify the double negative inside the parentheses into addition: y1=12(x+2)y - 1 = -\frac{1}{2}(x + 2) Distribute the 12-\frac{1}{2} systematically across the binomial elements: y1=12x1y - 1 = -\frac{1}{2}x - 1 Step 5 — Write in slope-intercept form. To strictly isolate yy, logically add 11 to both sides of the equality: y=12xy = -\frac{1}{2}x The final algebraic expression for the requested perpendicular line is y=12xy = -\frac{1}{2}x.

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Updated 2026-05-03

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