Question:

For what value of \(x\), the function \[ 2x^3+3x^2-36x+10 \] has minimum?

Show Hint

For minimum, use \(f'(x)=0\) and check \(f''(x)>0\).
  • \(-2\)
  • \(-3\)
  • \(2\)
  • \(3\)
Show Solution
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The Correct Option is C

Solution and Explanation


Step 1:
Let: \[ f(x)=2x^3+3x^2-36x+10 \]

Step 2:
Differentiate: \[ f'(x)=6x^2+6x-36 \] \[ f'(x)=6(x^2+x-6) \] \[ f'(x)=6(x+3)(x-2) \]

Step 3:
Critical points: \[ x=-3,\quad x=2 \]

Step 4:
Second derivative: \[ f''(x)=12x+6 \] At \(x=2\): \[ f''(2)=24+6=30>0 \]

Step 5:
Since second derivative is positive, minimum occurs at: \[ x=2 \] \[ \boxed{2} \]
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