SOLUTION: i need help with this two part question we started slope and i am lost and getting frustrated. can someone help me step by step explain what you did. 1.The distance of the poin

Algebra ->  Graphs -> SOLUTION: i need help with this two part question we started slope and i am lost and getting frustrated. can someone help me step by step explain what you did. 1.The distance of the poin      Log On


   



Question 620474: i need help with this two part question we started slope and i am lost and getting frustrated. can someone help me step by step explain what you did.
1.The distance of the point (1,5) from the line y = -2 x - 1
is

2.The equation of the line that goes through the point ( 4 ,6 ) and is perpendicular to the line 4 x + 2 y = 3 can be written in the form y = mx+b where m is and b is


Found 4 solutions by ewatrrr, Alan3354, lynnlo, Edwin McCravy:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 
Hi,
1.The distance of the point (1,5) from the line y = -2 x - 1
Blue line perpendicular to y = -2x+1 that passes thru (1,5) would be y = (1/2)x + 9/2
When the lines Intersect: +-2x%2B1+=+%281%2F2%29x+%2B+9%2F2 | x = (-11/5) and y = (17/5)
Distance between Points: D = sqrt+%28%28x%5B1%5D-x%5B2%5D%29%5E2%2B%28y%5B1%5D-y%5B2%5D%29%5E2%29%29
( 1, 5)
(-11/5, 17/5) D =

2. 2.The equation of the line that goes through the point ( 4 ,6 ) and is perpendicular to the line:
4x + 2y = 3 or y = -2x + 3/2, m = -2
New Line: m = (1//2) the negative reciprocal of -2
y = (1/2)x + b |\using Pt(4,6) to solve for b
6 = 2 + b
4 = b and y = (1/2)x + 4

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
1.The distance of the point (1,5) from the line y = -2x - 1
-----------------
This takes a few steps.
The distance is the minimum distance from the point to the line. That's the line perpendicular to the given line thru the point.
y = -2x - 1
Find the slope of y = -2x - 1
It's in slope-intercept form, y = mx + b, so the slope is -2.
The slope of lines perpendicular is the negative inverse, m = +1/2
--------------
Now find the equation of the line with slope 1/2 that passes thru the point (1,5).
----
Use y = mx + b and the point to find b, the y-intercept
5 = (1/2)*1 + b
b = 4.5
--> y = (1/2)x + 4.5 is the line thru (1,5) and perpendicular to y = -2x - 1
----------------
Find the point of intersection of the 2 lines.
y = -2x - 1
y = x/2 + 4.5
Since they both = y:
-2x-1 = x/2 + 4.5
-4x-2 = x + 9
x = -11/5 or -2.2
------
y = 3.4
--> point of intersection is (-2.2,3.4)
-----
Use the distance formula for the 2 points.
d+=+sqrt%28diffy%5E2+%2B+diffx%5E2%29+=+sqrt%281.6%5E2+%2B+3.2%5E2%29+=+sqrt%2812.8%29
d =~ 3.5777 units.
============================================
2.The equation of the line that goes through the point (4,6) and is perpendicular to the line 4x + 2y = 3 can be written in the form y = mx+b where m is and b is
-----------------
This is the same as the first part of #1.
Try it, email via the Thank You note for help or to check your work.
I'll bbl

Answer by lynnlo(4176) About Me  (Show Source):
You can put this solution on YOUR website!
(1) -2
(2) 4x+2y=3
rewrite in y=mx+b form
y=-2x+3/2
2x is m
3/2 is b

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
There is also a formula for your first problem:

The distance from the point 

(x1,y1) to the line whose equation is Ax + By + C = 0 

is given by the formula:

d = %28Ax%5B1%5D%2BBy%5B1%5D%2BC%29%2Fsqrt%28A%5E2%2BB%5E2%29

Your equation is 

y = -2x - 1

which is equivalent to

2x + y + 1 = 0

Compare that to

Ax + By + C = 0

and A=2, B=1, and C=1,  (x1,y1) = (1,5) 

Substitute in

d = %28Ax%5B1%5D%2BBy%5B1%5D%2BC%29%2Fsqrt%28A%5E2%2BB%5E2%29

d = %28%282%29%281%29%2B%281%29%285%29%2B1%29%2Fsqrt%282%5E2%2B1%5E2%29

d = %282%2B5%2B1%29%2Fsqrt%284%2B1%29

d = 8%2Fsqrt%285%29
d = 8%2Fsqrt%285%29·sqrt%285%29%2Fsqrt%285%29

d = 8sqrt%285%29%2F5 which is approximately 3.5777, as the other tutor found.

Edwin