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  1. J

    Discriminant of Characteristic Polynomial > 0

    Homework Statement Show that the descriminant of the characteristic polynomial of K is greater than 0. K=\begin{pmatrix}-k_{01}-k_{21} & k_{12}\\ k_{21} & -k_{12} \end{pmatrix} And k_i > 0 Homework Equations b^2-4ac>0 The Attempt at a Solution I have tried the following...
  2. J

    Differential Equation with Summation

    Homework Statement y''+0.1y'+y=1+2\sum_{k=1}^{n}(-1)^{k}u_{k\pi}(t) and quiescent initial conditions. Homework Equations None. The Attempt at a Solution (s^{2}+0.1s+1)Y(s)=\mathcal{L}\{1\}+2\sum_{k=1}^{n}(-1)^{k}\mathcal{L}\big\{ u_{k\pi}(t)\big\} I'm not sure if this step was...
  3. J

    Vectors Tension Question

    Homework Statement A 50 N sign is suspended by two cables that make angles of 25 degrees and 70 degrees with the horizontal. Determine the tension in each cable. Homework Equations Cosine law, sine law, or trig The Attempt at a Solution I believe that the teacher's answer is wrong. She...