SOLUTION: Hi I am needing a little help on some algebra. Could you help me solve this: Is the point (-120,-99) on the graph of the line. Y=4/5x-3? Explain why or why not. I have tried and

Algebra ->  Linear-equations -> SOLUTION: Hi I am needing a little help on some algebra. Could you help me solve this: Is the point (-120,-99) on the graph of the line. Y=4/5x-3? Explain why or why not. I have tried and       Log On


   

Question 93334: Hi I am needing a little help on some algebra. Could you help me solve this:
Is the point (-120,-99) on the graph of the line. Y=4/5x-3? Explain why or why not. I have tried and can't come up with anything. Thanks for your time
Found 2 solutions by Earlsdon, bucky:
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Is the point (-120, -99) on the graph of y+=+%284%2F5%29x-3?
If the given point is on the line then the x- and y-coordinates of the point will satisfy the equation.
To find out if this is true, you will substitute the x- and y-coordinates of the point (-120, -99) into the equation.
-99+=+%284%2F5%29%28-120%29-3 Evaluate this.
-99+=+-96-3
-99+=+-99
The answer is yes.

Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
The point (-120,-99) is in the standard form (x,y) which means x = -120 and y = -99.
If that point is on the graph of the line that represents the equation:
.
y+=+%284%2F5%29%2Ax+-3
.
then if you substitute -99 for y and -120 for x both sides of the equation will be
equal and that will prove that the point is on the line. Let's try it ...
.
Substituting -99 for y and -120 for x changes the equation to:
.
-99+=+%284%2F5%29%2A%28-120%29+-3
.
If you multiply %284%2F5%29%2A%28-120%29 you multiply the 4 times the -120 to get -480 and then you
divide that by the denominator 5 to get -96. Substituting -96 for %284%2F5%29%2A%28-120%29
the equation then becomes:
.
-99+=+-96+-+3
.
and on the right side if you combine -96 and - 3 you get -99. That reduces the equation to:
.
-99+=+-99
.
Both sides of the equation are equal when x = -120 and y = -99.
.
This shows the equation is true for the point (-120,-99). Therefore, since the x and y values
of the point make the equation true, you can say that the point (-120,-99) is on the graph
of the equation:
.
y+=+%284%2F5%29%2Ax+-3
.
Hope this helps you to understand the problem and what you have to do to show whether
points are or are not on the graph of an equation.
.