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Multiple Choice
Consider the function . What are the critical numbers of ?
A
,
B
C
,
D
,
Verified step by step guidance
1
Step 1: Recall that critical numbers occur where the derivative of the function is zero or undefined. Start by finding the derivative of q(x). The function is q(x) = 54x^4 + 125x. Use the power rule to differentiate each term.
Step 2: Apply the power rule to differentiate 54x^4, which gives 216x^3. Similarly, differentiate 125x, which gives 125. The derivative of q(x) is q'(x) = 216x^3 + 125.
Step 3: Set the derivative equal to zero to find the critical numbers. Solve the equation 216x^3 + 125 = 0.
Step 4: Rearrange the equation to isolate x^3. Subtract 125 from both sides to get 216x^3 = -125. Then divide both sides by 216 to get x^3 = -125/216.
Step 5: Solve for x by taking the cube root of both sides. This gives x = -∛(125/216). Additionally, check if x = 0 is a critical number by substituting it into q'(x). Since q'(0) = 125, x = 0 is not a critical number.