Solving Very Hard Integral g(x) - Joe

  • Thread starter Thread starter A_I_
  • Start date Start date
  • Tags Tags
    Hard Integral
A_I_
Messages
137
Reaction score
0
g(x) is a function of x that we do not know its form.


y(t) =(1/2) integral 0-->t [ sin(2t-2x)*g(x) ]dx

i tried to use integration by substitution and by parts
but the problem is that g(x) has an unknown form.

the actual problem is that

y" +cy' +dy = g(t) y(0) = y0 y'(0) = y'0

we are asked to find c,d,y0,y'0
knowing that y(t) is the solution of the second order differential equation.

i would appreciate your help.
Thanks,
Joe
 
Physics news on Phys.org
Evaluate y(0) to find y0.

Differentiate y and evaluate y'(0) to find y'0

Insert y' and y'' in your equation, and determine c and d from that.

Remember Leibniz' rule for differentiating an integral with variable limits!
 
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...
Back
Top