(Solved): Consider the function \[ f(x, y)=\ln \left(\sqrt{9 x^{2}+B y^{2}}\right) \] a. Find fyy . \[ f_{y y ...

Consider the function \[ f(x, y)=\ln \left(\sqrt{9 x^{2}+B y^{2}}\right) \] a. Find fyy . \[ f_{y y}(x, y \] b. What is \( f_{x x} \) ? \[ f_{x x}(x, y)= \] c. For what values of \( B \) does \( f \) satisfy the Laplace equation \( f_{x x}+f_{y y}=0 \) ? All values of \( B \) No values of \( B \) When \( B=9 \) (and only then) When \( B \neq 9 \) (and only then) When \( B=-9 \) (and only then) When \( B \neq-9 \) (and only then) When either \( B=9 \) or \( B=-9 \) (and only then) When both \( B \neq 9 \) and \( B \neq-9 \) (and only then)