Solving an Exact Differential Equation In Exercises 5-14, determine whether the differential equation is exact. If it is,find the general solution.
\(y e^{x} d x+e^{x} d y=0\)
Text Transcription:
y e^x dx+e^x dy=0
Step 1 of 5) Theorem 11—Second Derivative Test for Local Extreme Values Suppose that ƒ(x, y) and its first and second partial derivatives are continuous throughout a disk centered at (a, b) and that ƒx(a, b) = ƒy(a, b) = 0. Then i) ƒ has a local maximum at (a, b) if ƒxx 6 0 and ƒxx ƒyy - ƒxy 2 7 0 at (a, b). ii) ƒ has a local minimum at (a, b) if ƒxx 7 0 and ƒxx ƒyy - ƒxy 2 7 0 at (a, b). iii) ƒ has a saddle point at (a, b) if ƒxx ƒyy - ƒxy 2 6 0 at (a, b). iv) the test is inconclusive at (a, b) if ƒxx ƒyy - ƒxy 2 = 0 at (a, b). In this case, we must find some other way to determine the behavior of ƒ at (a, b).
