Question 130Asked in BPSC TRE 2.0 (2023) Mathematics Class 9-10 (Re-exam)

The equation xy − z log y + e^(xz) = 1 can be solved in a neighbourhood of the point (0, 1, 1) as y = f(x, z) for some continuously differentiable function…यदि समीकरण xy − z log y + e^(xz) = 1 को बिन्दु (0, 1, 1) के पड़ोस में, y = f(x, z) के रूप में हल किया जा सकता है किसी निरंतर अवकलनीय फलन f के लिए, तो

The equation xy − z log y + e^(xz) = 1 can be solved in a neighbourhood of the point (0, 1, 1) as y = f(x, z) for some continuously differentiable function f. Then
यदि समीकरण xy − z log y + e^(xz) = 1 को बिन्दु (0, 1, 1) के पड़ोस में, y = f(x, z) के रूप में हल किया जा सकता है किसी निरंतर अवकलनीय फलन f के लिए, तो
  1. A∇f(0, 1) = (2, 0)∇f(0, 1) = (2, 0)
  2. B∇f(0, 1) = (0, 2)∇f(0, 1) = (0, 2)
  3. C∇f(0, 1) = (0, 1)∇f(0, 1) = (0, 1)
  4. DMore than one of the aboveउपर्युक्त में से एक से अधिक
  5. ENone of the aboveउपर्युक्त में से कोई नहीं
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Correct answer: (A) ∇f(0, 1) = (2, 0)∇f(0, 1) = (2, 0)

Explanation

With F = xy − z log y + e^(xz) − 1, at (0, 1, 1): Fₓ = y + z e^(xz) = 2, F_y = x − z/y = −1, F_z = −log y + x e^(xz) = 0. So f_x = −Fₓ/F_y = 2 and f_z = −F_z/F_y = 0, giving ∇f(0, 1) = (2, 0).F = xy − z log y + e^(xz) − 1 के लिए (0, 1, 1) पर Fₓ = y + z e^(xz) = 2, F_y = x − z/y = −1, F_z = −log y + x e^(xz) = 0। अतः f_x = −Fₓ/F_y = 2 और f_z = −F_z/F_y = 0, इसलिए ∇f(0, 1) = (2, 0)।

From BPSC TRE 2.0 (2023) Mathematics Class 9-10 (Re-exam) — Previous Year Paper

This is question 130 of BPSC TRE 2.0 (2023) Mathematics Class 9-10 (Re-exam) — Previous Year Paper. See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.