SOLUTION: Hi there, My question: For this linear equation y=-(2/3) x+30 I have to graph the x and y intercepts, and determine the heigth of the laser beam when the laser is 30 feet from t

Question 408057: Hi there,
My question: For this linear equation y=-(2/3) x+30 I have to graph the x and y intercepts, and determine the heigth of the laser beam when the laser is 30 feet from the building...

For this linear equation y=-(2/3) x+30
A1} the Y axis represents the height (above ground) in feet.
A2} the X axis represents the distance (from the building) measured in feet.
This problem has asked me to interpret the results graphically. I have graphed the following values:
The x intercept or the point where the value crosses the x axis represents the point where the laser beams touches the ground. The y intercept, the point where the value crosses the y axis which represents the laser starting point or point where man is located.
A3} in the equation y=-(2/3) x+30 y=mx+b format (slope intercept)
(b) Represents the height of the window
(x)Represents the point where the light intercepts the ground.
A4} I solved this question by first drawing a grid, starting at the window point (0, 30)Then I used my slope of -2/3 to determine the value of 42 feet out from the building when the lights beam intercepts the ground. (42, 0)
I have found the light to be 42feet out (x value), 30feet high(y value) by using (rise over run) or slope of -2/3.
A5} Quadrant 2 is the only relevant quadrant for this problem. If we were doing a standard graphed linear equation, we would include quad. 1, 2 and 3 but since we are not including the area under the ground quad 3 is excluded, and since the beam is directional, quad 1 is also excluded. Quad four is also excluded because in either scenario, the plotted points are never on that plane/ quadrant.

A graph was a very good representation of the light because it clearly shows the path the light took to the ground, in a way that brings the problem to life. The graph gave a pictorial representation for each value. Y isn�t simply Y its now, the point where the light originated from. And x has a pictorial value as well; X is the place where the beam intersects the ground.
My work was returned to me because I did not find the x value correctly, I do not know how to go about finding this. I have graphed this problem but was not able to send a copy so that you could see my work,
x y=-(2/3)x+30
-1 30 2/3
0 30
1 29 1/3
I need to know what the height is in feet when the laser beam is 30 feet away from the building...
Thank you so much for your help!
Take care
Maranda

Found 2 solutions by solver91311, richard1234:
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

You are way way way over thinking this thing.

Take your equation and substitute 0 in place of x. Do the arithmetic. The value you get for y is the height of the window. Take the original equation and substitute 0 in place of y. Do the arithmetic. The value you get for x is the distance from the building where the beam hits the ground.

John

My calculator said it, I believe it, that settles it

Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
I agree with the other tutor, you're making the problem too complicated. You can find the y-intercept by replacing x = 0, and the x-intercept by replacing y = 0. Here's what the graph looks like:

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