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June 16th, 2017, 11:32 PM  #1 
Newbie Joined: Jun 2017 From: Australia Posts: 2 Thanks: 0  AlgeBRAAAAA! PLEASE HELP
please help, I have attached the problem !

June 17th, 2017, 02:01 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 18,847 Thanks: 1568 
A clearer version . . . Bridge.PNG 26. The crosssection of a platform is shown above. All measurements are in metres. (a) Find the height of the platform. (b) Find the crosssectional area of the platform. (c) Find the volume of the concrete required to $\ \ \ \,\,$ build this platform if it is 20 metres long. Answers: (a) The height of the platform is (1  (2)) metres = 3 metres. (b) Crosssectional area = $\displaystyle 3e^{2} + \int_{e^{2}}^e (1  \ln(x))dx = 3e^{2} + {\large[}2x  x*\ln(x){\large]}_{e^{2}}^e$ metres² = $\displaystyle \left(e  e^{2}\right)$ metres². (c) Required volume = $\displaystyle 20\left(e  e^{2}\right)$ metres³. 
June 17th, 2017, 03:40 AM  #3 
Math Team Joined: Jan 2015 From: Alabama Posts: 3,109 Thanks: 855 
But this is definitely not an "algebra", not even an "AlgeBRAAAAA" problem!

June 21st, 2017, 05:18 PM  #4 
Newbie Joined: Jun 2017 From: New York Posts: 1 Thanks: 0  Where you should start.
Calculus was invented as a tool for solving problems. Prior to the development of calculus, there were a variety of different problems that could not be addressed using the mathematics that was available. For example, scientists did not know how to measure the speed of an object when that speed was changing over time. Also, a more effective method was desired for finding the area of a region that did not have straight edges. Geometry, algebra, and trigonometry, which were well understood, did not provide the necessary tools to adequately address these problems.
Last edited by skipjack; August 7th, 2017 at 07:44 PM. 
June 21st, 2017, 05:39 PM  #5 
Senior Member Joined: Sep 2015 From: USA Posts: 1,862 Thanks: 968 
thanks for cutting and pasting that Quora article (without tribute) on the history of calculus. I'm sure that it helped the OP no end.

June 21st, 2017, 05:41 PM  #6 
Senior Member Joined: Aug 2012 Posts: 1,856 Thanks: 513  I thought it was a plot to make students miserable. Skipjack, where did $e^{2}$ come from? That's not on OP's diagram, and of course without some clue we don't know what the negative $y$value is for the bottom of the shape. 