Please help set up this problem. "For a 225 watt bulb, the intensity (I) of light in lumens at a distance of x feet is (I)=225/x^2. What is the intensity of the light 5 feet from the bulb. ". This is a simple inverse relationship. So I know that I need to set up the function as f(x) = polynomial/polynomial. The graph will be y=a/x-b+c. The original is given, I=225/x^2. I do not know how to move from what is given to a place where I can solve for the lumens at 5 feet. Any help would be most appreciated.

Question

anonymous · Answer

you could just plug 5 into the given equation

anonymous · Answer

225/5^2 would give 9 lumens. I got that part right off. But the question is asking for the inverse relationship, to graph. I am lost about how to find the values for the graph, given that I only have one product as my answer, the 9 lumens.

anonymous · Answer

to find the values to graph, plug in more x's, get the I's, and plot them as coordinates (x, I)

anonymous · Answer

So could I use any values for the x-value?

anonymous · Answer

they have to be positive (because you cant have a negative distance...even though it wouldnt really matter in the context of the equation because youre squaring the distance, resulting in a positive number always, but based on the problem, you cant put in negative x's)

anonymous · Answer

ok. I think I got it. Thanks so much!

anonymous · Answer

welcome :)