Implicit Differentiation with Two Equations
Description
Using implicit differentiation, compute the derivatives dydx and dzdx implicitly from the equations fx,y,z=gx,y,z and Fx,y,z=Gx,y,z.
Enter equations:
y2−2 x z=1
y2−2⁢x⁢z=1
x2−cosx z=y
x2−cos⁡x⁢z=y
Obtain dydx:
implicitdiff,, y,z, y,x
−2⁢xsin⁡x⁢z⁢y−1
Obtain dzdx:
implicitdiff,,y,z,z,x
−2⁢y⁢x+z⁢sin⁡x⁢z⁢y−zsin⁡x⁢z⁢y−1⁢x
Stepwise Calculation:
Replace y with yx and z with zx:
eval,, y=yx,z=zx
y⁡x2−2⁢x⁢z⁡x=1,x2−cos⁡x⁢z⁡x=y⁡x
Apply ddx:
diff,x
2⁢y⁡x⁢ⅆⅆx⁢y⁡x−2⁢z⁡x−2⁢x⁢ⅆⅆx⁢z⁡x=0,2⁢x+sin⁡x⁢z⁡x⁢z⁡x+x⁢ⅆⅆx⁢z⁡x=ⅆⅆx⁢y⁡x
Solve for both derivatives:
solve, diffyx,x,diffzx,x1
ⅆⅆx⁢y⁡x=−2⁢xsin⁡x⁢z⁡x⁢y⁡x−1,ⅆⅆx⁢z⁡x=−2⁢y⁡x⁢x+z⁡x⁢sin⁡x⁢z⁡x⁢y⁡x−z⁡xsin⁡x⁢z⁡x⁢y⁡x−1⁢x
Replace yx and zx with y and z, respectively:
d__y__d__x__, d__z__d__x__=evalrhs1,rhs2,yx=y, zx=z
dydxdzdx=−2⁢xsin⁡x⁢z⁢y−1−2⁢y⁢x+z⁢sin⁡x⁢z⁢y−zsin⁡x⁢z⁢y−1⁢x
Commands Used
diff, eval, implicitdiff, isolate, rhs
See Also
Student[Calculus1][DiffTutor]
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