Q. The equation of line k is y−2=21(x−6). Perpendicular to line k is line ℓ, which passes through the point (−1,−6). What is the equation of line l?
Determine slope of line k: Determine the slope of line k. The equation of line k is given in point-slope form: y−2=21(x−6). The slope of line k is the coefficient of (x−6), which is 21.
Find slope of line ℓ: Find the slope of line ℓ, which is perpendicular to line k. Since line ℓ is perpendicular to line k, its slope will be the negative reciprocal of the slope of line k. The negative reciprocal of 21 is −2. Therefore, the slope of line ℓ is −2.
Use point-slope form: Use the point-slope form to write the equation of line ℓ. Line ℓ passes through the point (−1,−6) and has a slope of −2. The point-slope form of a line is y−y1=m(x−x1), where m is the slope and (x1,y1) is a point on the line. Plugging in the slope and the point into the point-slope form, we get y−(−6)=−2(x−(−1)).
Simplify equation of line ℓ: Simplify the equation of line ℓ. Simplify the equation from the previous step: y+6=−2(x+1). Distribute the −2: y+6=−2x−2. Subtract 6 from both sides to get the equation in slope-intercept form: y=−2x−8.
More problems from Write an equation for a parallel or perpendicular line