Answer:
y = (2/3)y - 2
Explanation:
Linear equations of the form y=mx+b, describe the slope, m, and the y-intercept, b (the value of y when x=0).
Line K
y = -(3/2)x + 1 tells us that it has a slope of -(3/2) and crosses the y axis (x=0) at y = 1.
Perpendicular Lines
Perpendicular lines have a useful property in that they have a slope that is the "negative inverse" of the line they are perpendicular to. If, for example, we were ever asked what is the slope of a line perpendicular to Line L (yes, it happens), we could, with minimal effort, respond "It is the negative inverse of -(3/2)," which is a slope of (2/3).
Line L
We just accidently answered a key question when we found the negative inverse of the slope for Line K, (2/3). That will be the slope of Line L that will make it perpendicular to Line K.
Line L will have the form y = (2/3)x + b
This line will be perpendicular to Line K, no matter the value of b. But we want a perpendicular line that goes through point (6,2), so we need to find a value of b that will force it to go through that point.
The role b has in our equation is simply moving it up or down. If b were 0, the line will go through the origin (0,0). If b were 5, it would interect the y axis at 5 (0,5). We could draw a graph and get a pretty good idea what b would have to be for the line to go throgh (6,2), but most prefer the easier route: Use the (x,y) value in the above equation and solve for b. Its easy, and works great:
y = (2/3)x + b for (6,2)
2 = (2/3)(6) + b
b = 2 - (2/3)*(6)
b = 2 - 4
b = -2
The equation for Line L is thus: y = (2/3)y - 2
See the attached graph. Included are equations [marked Demo Line 1 and 2] with 2 random values of b (1 and 0), in order to:
- demonstrate how b impacts the line, and
- suggest try using DESMOS as a free online graphing tool.