Hi, Could someone please explain the solution to the integration by part given as the solution to this? Stupid question but I don't understand why [-(1.1x - 3000) * 7500^4/(7500+x)^4 ] between the limits of infinity and 3000/1.1 is zero. I'm sorry if this is very basic. Any help much appreciated. Thanks, Tom
I think its (b) of (ii) part that you are asking? Well, this will become zero because firstly when you put the limit ∞, the denominator will be infinity of second term i.e. 7500⁴/(7500+x)⁴ since x is in denominator and 1/∞=0. And then, when you put the lower limit 3000/1.1 in x, the first term i.e. (1.1x-3000) will be zero. And both terms are in multiplication. So, overall it becomes zero.
