Zen F. answered 10/28/20
Middle and High School Math Tutor
Through: (1,-2), perp. yo y=1/5x+5
The line is in the slope intercept form so.....
y=1/5x+5 ............this is the slope intercept form....y = mx + b....where m = slope
Through: (1,-2), perp. y=1/5x+5
You want to research and verify the following 2 principles related to perpendicular lines.
The slopes of two perpendicular lines are negative reciprocals.
The product of the slopes of two perpendicular lines is -1 since
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Through: (1,-2), perp. y=1/5x+5
We need the slope.....or the m portion of the equation so for the line....rewritten we have...
y=1/5x+5.....the slope is m = 1/5....Right?
Now using the given principles a line perpendicular to this one has a slope that is the negative reciprocal...hmmm
.....let's see....the reciprocal is 1/x....so the reciprocal in this case 5......but we are not done yet...
...the slope for a perpendicular line is "negative reciprocal".....so -5 is the slope of 2nd line....
....verify.....1/5 * -5 = -1.......that verifies the 2nd principle above.......
Through: (1,-2), perp. y=1/5x+5
....we also want the line to pass through a certain point....that is important because we can use the "point-slope" version of a line to find the equation of the 2nd line....like so.....
y−y1=m(x−x1).......y-(-2)=-5 (x - 1)......or y + 2= -5 (x-1)......or y + 2 = -5 x + 5
....subtract 2 from both sides......we have.....Y = -5 x + 5 - 2. or...y = -5 x + 3
..check the point (1,-2).....-2= -5 (1) + 3 =-2..it checks perfectly....
so the line y = -5 x + 3
....IS PERPENDICULAR TO THE LINE...
.....y=1/5x+5.....Correct?
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You can also GRAPH both of these lines to literally SEE the perpendicular lines cross each other......