SOLUTION: write an equation for each line, then graph the line. through (-1,3) and parallel to y=2x+1 through (2,2) and perpendicular to y=-3/5x+2 through (-3,4) and vertical thr

Algebra ->  Linear-equations -> SOLUTION: write an equation for each line, then graph the line. through (-1,3) and parallel to y=2x+1 through (2,2) and perpendicular to y=-3/5x+2 through (-3,4) and vertical thr      Log On


   



Question 211448: write an equation for each line, then graph the line.
through (-1,3) and parallel to y=2x+1
through (2,2) and perpendicular to y=-3/5x+2
through (-3,4) and vertical
through (4,1) and horizontal

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!
You must learn some facts about lines, their graphs
and their equations.

(1). The equation of a non-vertical graphed line that goes through point
(x1,y1) and has slope m is

(2). y-y%5B1%5D=m%28x-x%5B1%5D%29

(3). The equation of a non-vertical graphed line that has slope m and 
y-intercept %22%280%2Cb%29%22 is 

y=mx%2Bb

(4). Two non-vertical parallel lines have the same slope.

(5). Two non-vertical perpendicular lines have slopes one of which
is the reciprocal of the other with the sign changed.

(6). A vertical line has no slope and has the equation x+=+a where
a represents its distance from the y-axis, right of the y-axis
if a is positive and left of the y-axis if a is negative.
x=0 is the equation of the vertical line that coincides with
the y-axis.

(7). A horizontal line has slope m=0.

-----------------------------

write an equation for each line, then graph the line.

through (-1,3) and parallel to y=2x%2B1

We draw the line y=2x%2B1 by plotting a couple of points
and draw it in light green:



Next we plot the point (-1,3)



And we draw a black line through that point 
parallel to the green line:



That black line is the line we need the equation for.

So, from y=2x%2B1 we use (3) above to find that m=2

From (4) we know that we will use the same slope m=2.

Next we use (1) to find the equation:

y-y%5B1%5D=m%28x-x%5B1%5D%29 where (x1,y1) = (-1,3)
and m=2

y-3=2%28x-%28-1%29%29
 
y-3=2%28x%2B1%29

y-3=2x%2B2

y=2x%2B5

-------------------------

through (2,2) and perpendicular to y=%28-3%2F5%29x%2B2

We draw the line y=%28-2%2F3%29x%2B2 by plotting a couple of points
and draw it in light green:



Next we plot the point (2,2)



And we draw a black line through that point 
perpendicular to the green line:



That black line is the line we need the equation for.

So, from y=%28-3%2F5%29x%2B2 we use (3) above to find that m=-3%2F5

From (5) we know that we will use the slope which is found
by inverting -3%2F5 and changing its sign, and so we
use m=5%2F3 for the black line.

Next we use (1) to find the equation:

y-y%5B1%5D=m%28x-x%5B1%5D%29 where (x1,y1) = (2,2)
and m=5%2F3

y-2=%285%2F3%29%28x-2%29
 
y-2=%285%2F3%29%28x-2%29

y-2=%285%2F3%29x-10%2F3

y=%285%2F3%29x-10%2F3%2B2

y=%285%2F3%29x-10%2F3%2B6%2F3

y=%285%2F3%29x-4%2F3


-------------------------

through (-3,4) and vertical

We plot the point:



and draw a vertical line through it:



Now we use (6) above and realize that the vertical line is 3
units to the left of the the y-axis and thuse its equation
is x=-3

--------------------------------

through (4,1) and horizontal

We plot the point:



and draw a horizontal line through it:



Now we use (7) above which tells us the slope m=0

Next we use (1) to find the equation:

y-y%5B1%5D=m%28x-x%5B1%5D%29 where (x1,y1) = (4,1)
and m=0

y-1=0%28x-4%29
 
y-1=0

y=1


--------------------------------
Edwin