SOLUTION: Given the linear equation y = 3/4x-2, find the y-coordinates of the points (-8, ), (-4, ), and (4, ). Please show all of your work. Plot those points and graph the linear equati

Algebra ->  Linear-equations -> SOLUTION: Given the linear equation y = 3/4x-2, find the y-coordinates of the points (-8, ), (-4, ), and (4, ). Please show all of your work. Plot those points and graph the linear equati      Log On


   



Question 458436: Given the linear equation y = 3/4x-2, find the y-coordinates of the points (-8, ), (-4, ), and (4, ). Please show all of your work. Plot those points and graph the linear equation.
Found 2 solutions by richwmiller, MathLover1:
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
plug in the x values and find y

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

Given the linear equation y+=+%283%2F4%29x-2, find the y-coordinates of the points
x=-8
y+=+%283%2F4%29%28-8%29-2=-24%2F4-2=-6-2=-8
x=-4
y+=+%283%2F4%29%28-4%29-2=-12%2F4-2=-3-2=-5
x=4
y+=+%283%2F4%29%284%29-2=12%2F4-2=3-2=1

so, the y-coordinates are
(-8, -8 ), (-4, -5 ), and (4,1 )
check if these 3 points lie in a same line

Solved by pluggable solver: To determine if 3 points lie in a line
The 3 points lie on a same plane. For all points to lie on a line they should satisfy the equation of a line. Hence any two points taken on a line should calculate to the same slope of a line.

In order to prove the 3 points to lie on a line, as there exists a unique line containing three points and every line has a unique slope.
Hence it will be sufficient to prove that the slope calculated taking 2 points at a time should be equal.


Slope of line taking points (X1,Y1) and (X2,Y2) is

slope+=+%28Y2-Y1%29%2F%28X2-X1%29


slope+=+%28%28-5--8%29%2F%28-4--8%29%29+=+0.75 ........................(1)



Slope of line taking points (X3,Y3) and (X1,Y1) is

slope+=+%28Y3-Y1%29%2F%28X3-X1%29


slope+=+%28%281--8%29%2F%284--8%29%29+=+0.75 ........................(2)



From conditions (1) and (2)


The slopes are equal hence the 3 points can lie on same line.


If the slope calculated from points (X2,Y2) and (X3,Y3) comes out to be same then it is confirmed that the 3 points lie on a same line.



slope+=+%28Y3-Y2%29%2F%28X3-X2%29


slope+=+%28%281--5%29%2F%284--4%29%29+=+0.75 ........................(3)


From (1),(2) and (3)

Hence, It is proved that the 3 points lie on same line.


To read more on equations of a line refer to articles on wikipedia


let's see the graph:

+graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+%283%2F4%29x-2%29+