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  1. J

    Laplace transform

    Homework Statement I already got Q(s)=150/(s(s^2+20s+200)), then i complete the square on the quadratic. I got Q(s)=150/(s((s+10)^2+10^2))). But then i cant find the Q(t) because the equation (s+10)^2+10^2=0 dosent have roots. Or i have to use complex numbers ? So I am confused. Homework...
  2. J

    Find the general solution

    Homework Statement Find the general solution of: dy/dx=lnx/(xy+xy^3) Homework Equations The Attempt at a Solution In order to find the general solution, i rerrange the equation to:(y+y^3)dy=(lnx/x)dx, then int(y+y^3)dy=int(lnx/x)dx, then i got 2(lnx)^2=2y^2+y^4. then i rerange y...
  3. J

    Differentiation the integral

    Homework Statement Let f (x) =int(x,0) x sin(t^2)dt. Show that f''(x)= 2 sin(x^2) + 2x2 cos(x^2) Homework Equations The Attempt at a Solution I cant get f''(x)= 2 sin(x^2) + 2x2 cos(x^2), i can only get f''(x)= sin(x^2) + 2x2 cos(x^2). Because f'(x)=xsin(x^2). can anyone see...