How to Solve Multivariable Calculus Problems with Two Variables: Tips and Tricks

rmunoz
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Integral and Derivative Help!

Homework Statement


I have 3 problems that i am struggling to solve for the simple fact that there are two variables in each problem. I have no experience with multivariable calculus... i feel like I am missing something big because i have all the prerequisites for this physics course completed and with high grades yet this is our first hw... stuff we should be familiar with.
1. \int 1/(d-x) dx

2. derivative of f(t)= sin(\omegat -1)

3. \int x/((x^2)+(L^2))^(3/2) dx

Homework Equations





The Attempt at a Solution


I've tried to solve 1 and 3 using trig substitution, partial fractions, integration by parts, u substitution but they all seem to lead to dead ends
 
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Assume 'd' and 'L' are constants. The first is a simple u-substitution. The second one, apply the chain rule.
 


The third one is a simple substitution as well. You could also do it with a trig substitution.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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