Questions: Find the derivative of the following function.
f(x) = 3x^4 + 9/x^5 - 8x + 10
A. f'(x) = 12x^3 + 9/x^5 - 8
B. f'(x) = 12x^3 - 45/x^6
C. f'(x) = 3x^3 - 45/x^5 + 2
D. f'(x) = 12x^3 - 45/x^6 - 8
Transcript text: Find the derivative of the following function.
\[
f(x)=3 x^{4}+\frac{9}{x^{5}}-8 x+10
\]
A. $f^{\prime}(x)=12 x^{3}+\frac{9}{x^{5}}-8$
B. $f^{\prime}(x)=12 x^{3}-\frac{45}{x^{5}}$
C. $f^{\prime}(x)=3 x^{3}-\frac{45}{x^{5}}+2$
D. $f^{\prime}(x)=12 x^{3}-\frac{45}{x^{6}}-8$
Solution
Solution Steps
Step 1: Differentiate each term separately
The function is \( f(x) = 3x^{4} + \frac{9}{x^{5}} - 8x + 10 \). To find the derivative \( f'(x) \), differentiate each term individually.
Step 2: Apply the power rule to \( 3x^{4} \)
The derivative of \( 3x^{4} \) is:
\[
\frac{d}{dx}(3x^{4}) = 3 \cdot 4x^{3} = 12x^{3}.
\]
Step 3: Apply the power rule to \( \frac{9}{x^{5}} \)
Rewrite \( \frac{9}{x^{5}} \) as \( 9x^{-5} \). The derivative is:
\[
\frac{d}{dx}(9x^{-5}) = 9 \cdot (-5)x^{-6} = -\frac{45}{x^{6}}.
\]
Step 4: Apply the power rule to \( -8x \)
The derivative of \( -8x \) is:
\[
\frac{d}{dx}(-8x) = -8.
\]
Step 5: Differentiate the constant term \( 10 \)
The derivative of a constant is zero:
\[
\frac{d}{dx}(10) = 0.
\]
Step 6: Combine the derivatives
Combine the derivatives of all terms to get:
\[
f'(x) = 12x^{3} - \frac{45}{x^{6}} - 8.
\]
Final Answer
The correct answer is D. \(f^{\prime}(x)=12 x^{3}-\frac{45}{x^{6}}-8\)