The GATE Grind

GATE 2021 MA – Question 50

Real Analysis · Multivariable Analysis · 2 marks · Multiple choice

The equation xy−z log y+e^(xz)=1 defines y=f(x,z) near (x,y,z)=(0,1,1). Find ∇f(0,1).

  1. (2,0)
  2. (0,2)
  3. (0,1)
  4. (1,0)

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) (2,0)

Explanation

Set F=xy−z log y+e^(xz)−1. At the point, F_x=y+ze^(xz)=2,F_y=x−z/y=−1 and F_z=−log y+xe^(xz)=0. Since F_y≠0, the implicit function theorem applies and (f_x,f_z)=−(F_x,F_z)/F_y=**(2,0), A**.

More Multivariable Analysis questions

All Multivariable Analysis questions →