Explanation:For the square root to be defined in real numbers, the argument must be non-negative: , which implies .
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2If depends on the path along which approaches , then:
A.The limit exists and equals 0
B.The limit exists but is infinite
C.The limit does not exist
D.The function is continuous at
Correct Answer: The limit does not exist
Explanation:For a limit to exist in multivariable calculus, it must be unique regardless of the path taken to approach the point.
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3Evaluate .
A.$1$
B.$5$
C.$7$
D.$0$
Correct Answer: $1$
Explanation:Since the function is a polynomial, it is continuous everywhere. By direct substitution: .
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4What is the value of ?
A.$0$
B.$1$
C.
D.Does not exist
Correct Answer: Does not exist
Explanation: approaching along the x-axis (), the limit is $1$. Approaching along the y-axis (), the limit is . Since limits are different, it does not exist.
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5A function is continuous at if:
A. exists
B. is defined
C.
D. and exist at
Correct Answer:
Explanation:This is the formal definition of continuity: the limit must exist, the function must be defined, and the limit must equal the function value.
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6For , find the partial derivative .
A.
B.
C.
D.
Correct Answer:
Explanation:Treating as a constant: derivative of is and derivative of is .
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7For , find .
A.
B.
C.
D.
Correct Answer:
Explanation:Differentiating with respect to , is constant. Using chain rule: derivative of is . Here , so .
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8Clairaut's Theorem (or Schwarz's Theorem) states that under continuity conditions of second partial derivatives:
A.
B.
C.
D.
Correct Answer:
Explanation:The theorem asserts that mixed partial derivatives are equal if the second partial derivatives are continuous.
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9If , then is:
A.
B.
C.
D.
Correct Answer:
Explanation:Using chain rule: . Here , so .
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10If is differentiable at a point, then:
A.It must be continuous at that point
B.It is not necessarily continuous at that point
C.Only partial derivatives exist, but limit may not
D.The limit depends on the path
Correct Answer: It must be continuous at that point
Explanation:Differentiability implies continuity for multivariable functions (though continuity does not imply differentiability).
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11The total differential of a function is given by:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the standard definition of the total differential, representing the linear approximation of the change in .
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12If , calculate the approximate change in if changes from 2 to 2.01 and changes from 3 to 2.98.
A.$0.01$
B.
C.$0.05$
D.
Correct Answer:
Explanation:. At , . . .
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13Given where and , the Chain Rule for is:
A.
B.
C.
D.
Correct Answer:
Explanation:This formula represents the total derivative of with respect to the independent variable through intermediate variables and .
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14If , , , what is ?
A.
B.
C.$0$
D.$2$
Correct Answer:
Explanation:. Therefore, .
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15A function is homogeneous of degree if:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the definition of a homogeneous function of degree .
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16What is the degree of homogeneity of the function ?
A.$1$
B.$2$
C.$3$
D.$0$
Correct Answer: $2$
Explanation:. Degree is 2.
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17Euler's Theorem for a homogeneous function of degree states that:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the mathematical statement of Euler's Theorem on Homogeneous Functions.
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18If , the value of is:
A.$1$
B.
C.$0$
D.
Correct Answer: $0$
Explanation:Both terms are homogeneous functions of degree 0 (powers of cancel out). Thus . By Euler's theorem, the sum is .
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19If is a homogeneous function of degree in and , then equals:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the extension of Euler's theorem for second order derivatives.
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20Determine the degree of the homogeneous function .
A.
B.
C.$1$
D.$0$
Correct Answer:
Explanation:Numerator degree is , denominator degree is $1$. Total degree .
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21If , what is the value of ?
A.
B.
C.
D.
Correct Answer:
Explanation:Let . is homogeneous of degree . By modified Euler's, .
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22Which of the following is a stationary point condition for ?
A. and
B. and
C.
D. and
Correct Answer: and
Explanation:Critical or stationary points occur where the first order partial derivatives are simultaneously zero.
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23Let at a critical point . If and , then is a:
A.Local Maximum
B.Local Minimum
C.Saddle Point
D.Point of inflection
Correct Answer: Local Minimum
Explanation:The Hessian determinant positive () indicates an extremum. (convex up) indicates a minimum.
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24Let at a critical point . If , then is a:
A.Local Maximum
B.Local Minimum
C.Saddle Point
D.Test Inconclusive
Correct Answer: Saddle Point
Explanation:A negative Hessian determinant implies the curvature is different in different directions, forming a saddle point.
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25If at a critical point, then:
A.It is a Maximum
B.It is a Minimum
C.It is a Saddle Point
D.The test is inconclusive
Correct Answer: The test is inconclusive
Explanation:When the discriminant is zero, the second derivative test fails, and further investigation is needed.
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26Find the critical point of .
A.
B.
C.
D.
Correct Answer:
Explanation:. .
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27The Lagrange Multiplier method is used to find:
A.Roots of a polynomial
B.Area under a curve
C.Maxima or minima subject to constraints
D.Partial derivatives
Correct Answer: Maxima or minima subject to constraints
Explanation:Lagrange multipliers are specifically designed for optimization problems where variables are restricted by a constraint equation .
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28To find the extrema of subject to using Lagrange multiplier , we solve the system generated by:
A. and
B.
C.
D.
Correct Answer: and
Explanation:The condition states that the gradient of the function must be parallel to the gradient of the constraint curve.
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29The auxiliary function (Lagrange function) for maximizing subject to is:
A.
B.
C.
D.
Correct Answer:
Explanation:This defines the Lagrangian function whose unconstrained critical points correspond to the constrained critical points of .
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30Given , the value of is:
A.$1$
B.$0$
C.
D.
Correct Answer: $0$
Explanation:Let . By chain rule, summing the partials results in terms canceling out (e.g., , etc.).
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31If and , find the Jacobian .
A.
B.
C.$1$
D.
Correct Answer:
Explanation:.
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32If and are functionally dependent, their Jacobian is:
A.$1$
B.
C.$0$
D.Constant
Correct Answer: $0$
Explanation:The vanishing of the Jacobian determinant is a necessary and sufficient condition for functional dependence.
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33For the function , the point is a:
A.Local Maximum
B.Local Minimum
C.Saddle Point
D.Global Maximum
Correct Answer: Saddle Point
Explanation:. . Negative discriminant implies a saddle point.
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34The equation of the tangent plane to at is:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the standard linearization formula representing the tangent plane.
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35If , then is:
A.
B.
C.
D.
Correct Answer:
Explanation:Power rule applies when differentiating with respect to the base while holding exponent constant.
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36If , then is:
A.
B.
C.
D.
Correct Answer:
Explanation:Exponential rule applies when differentiating with respect to the exponent (like ): derivative is .
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37A function has a local maximum at if:
A. and
B. and
C.
D. and
Correct Answer: and
Explanation:Positive discriminant means extremum; negative second derivative () means concave down (Maximum).
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38Which of the following functions is homogeneous?
A.
B.
C.
D.
Correct Answer:
Explanation:Replace with and with : . It is homogeneous of degree 3. The constant 5 in option A breaks homogeneity.
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39If is differentiable, can be written as:
A.
B.
C.
D.
Correct Answer:
Explanation:This is the definition of differentiability, where as .
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40Compute for .
A.
B.
C.
D.
Correct Answer:
Explanation:. Then differentiate w.r.t : .
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41If and , calculate the Jacobian .
A.
B.
C.$1$
D.
Correct Answer:
Explanation:. Det = .
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42When finding the shortest distance from a point to a plane using Lagrange multipliers, the objective function is usually taken as:
A.The distance formula
B.The square of the distance
C.The equation of the plane
D.The gradient vector
Correct Answer: The square of the distance
Explanation:Minimizing the square of the distance is equivalent to minimizing the distance itself (since distance is non-negative) and avoids dealing with square roots during differentiation.
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43Implicit differentiation: If defines as a function of , then ?
A.
B.
C.
D.
Correct Answer:
Explanation:Derived from the total differential . If is constant (), .
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44Determine the limit .
A.$0$
B.
C.Does not exist
D.$1$
Correct Answer: Does not exist
Explanation:Along , limit becomes , which depends on . Hence limit does not exist.
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45Given , equals:
A.$0$
B.$1$
C.
D.
Correct Answer: $0$
Explanation:This function satisfies the Laplace equation. . By symmetry . Sum is 0.
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46Which of the following is NOT an indeterminate form for limits?
A.
B.
C.
D.
Correct Answer:
Explanation: is simply 0, which is determinate. The others are indeterminate forms.
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47For the function , at the origin :
A.Partial derivatives exist
B.Function is differentiable
C.Function is continuous but partial derivatives do not exist
D.Function is discontinuous
Correct Answer: Function is continuous but partial derivatives do not exist
Explanation:The function is continuous, but implies sharp corners at axes. involves limit of , which does not exist.
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48If is homogeneous of degree , then equals:
A.
B.
C.
D.
Correct Answer:
Explanation:From Euler's: First term group is , second term group is . Sum = .
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49In the method of Lagrange multipliers for a function of three variables subject to one constraint, how many equations must be solved?
A.$3$
B.$4$
C.$5$
D.$2$
Correct Answer: $4$
Explanation:Three equations from gradients () plus the constraint equation .
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50The gradient vector points in the direction of:
A.Maximum rate of decrease
B.Maximum rate of increase
C.Zero change (along contour)
D.Any arbitrary direction
Correct Answer: Maximum rate of increase
Explanation:A fundamental property of the gradient vector is that it points in the direction of the steepest ascent (maximum rate of increase) of the function.
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