Applications of integration: Area and boundaries? (can't understand solution)

Poppietje

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Hey! First of all, thank you for those who have set up this forum, I'm really happy that helpful online communities like this exist. :) I hope I can be of help too in the future, but now I'm here with a bit of a problem!

We are currently dealing with applications of integration in our calculus course, and one of our homework problems is giving me a bit of a headache.

You are given two functions: f(x) = 2x*sqrt(x) and g(x) = -2x + 24 that intersect at points (4, 16).
One of the questions goes as follows: Find the center of gravity of the area bounded by the two axes and the graph of g(x).

I am not sure how to find the initial area.
I found that when an area is bounded by an axis and a function, then the axis sets the lower boundary as 0. But indeed, that isn't the case here. The solution to the homework is given that the A = 1/2 * 12 * 24 = 144, and the integral boundaries are 0 to 12, but I'm honestly not sure where this solution comes from.
I'm pretty sure that the solution is D'Oh simple, but my brain just isn't picking up the pieces now. :roll: If you could give me a bit of a kick in the right direction so that I can figure out why is how and what, I would appreciate it so much!

Thank you!
 
Hey! First of all, thank you for those who have set up this forum, I'm really happy that helpful online communities like this exist. :) I hope I can be of help too in the future, but now I'm here with a bit of a problem!

We are currently dealing with applications of integration in our calculus course, and one of our homework problems is giving me a bit of a headache.

You are given two functions: f(x) = 2x*sqrt(x) and g(x) = -2x + 24 that intersect at points (4, 16).
One of the questions goes as follows: Find the center of gravity of the area bounded by the two axes and the graph of g(x).

I am not sure how to find the initial area.
I found that when an area is bounded by an axis and a function, then the axis sets the lower boundary as 0. But indeed, that isn't the case here. The solution to the homework is given that the A = 1/2 * 12 * 24 = 144, and the integral boundaries are 0 to 12, but I'm honestly not sure where this solution comes from.
I'm pretty sure that the solution is D'Oh simple, but my brain just isn't picking up the pieces now. :roll: If you could give me a bit of a kick in the right direction so that I can figure out why is how and what, I would appreciate it so much!

Thank you!

I am assuming that the problem meant "...of the area bounded by the (positive sides) of two axes and the graph of g(x)"

Plot the function g(x) = -2x + 24

Do you see the triangular area between (0,24), (0,0) and (12,0) - that is the area of interest.
 
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