Let f(x) = x3 + 15x2 - 33x - 36 be a real-valued function. Which of the following statements is/are TRUE?
Topic-wise GATE CS PYQs with verified steps
GATE CSE 2023 · Q28
Time
Select all that applyOne or more correct
Solution
Official answer: B) f(x) has a local maximum.; D) f(x) has a local minimum.
CalculusTo determine the local extrema of the function , find its first derivative:
Set to find the critical points:
Thus, the critical points are and .
Now, compute the second derivative:
Evaluate the second derivative at the critical points:
At :
Since $f''(-11) < 0$, $f(x)$ has alocal maximum at .
At :
Since $f''(1) > 0$, $f(x)$ has alocal minimum at .
Therefore, statements (B) and (D) are TRUE, while (A) and (C) are FALSE.
Try the question first, then check your work.
Examiner trap
Differentiate to find critical points where , then apply the second derivative test to classify each point.
This Calculus previous year question is Q28 of the GATE CSE 2023 paper. Find more GATE CSE PYQs on Calculus in Engineering Mathematics, or browse all GATE CSE PYQs.
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Calculus has 40 GATE CSE PYQs across 25 papers from 2011 to 2026. 2 of them are 1-mark MSQs like this one, and GATE CSE 2023 has 2.
How GATE tests CalculusIndependent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.