Question

28 f(x)=13-5x²

Explanation:

Assuming we need to find the derivative of \( f(x) = 13 - 5x^2 \) (a common calculus task with such a function):

Step 1: Recall derivative rules

The power rule: \( \frac{d}{dx}(x^n) = nx^{n - 1} \), and the derivative of a constant is 0. Also, the derivative of a sum/difference is the sum/difference of derivatives.

Step 2: Differentiate term by term

For \( f(x)=13 - 5x^2 \), the derivative \( f'(x)=\frac{d}{dx}(13)-\frac{d}{dx}(5x^2) \).
The derivative of 13 (a constant) is 0. For \( 5x^2 \), using the power rule and constant multiple rule: \( \frac{d}{dx}(5x^2)=5\times\frac{d}{dx}(x^2)=5\times2x^{2 - 1}=10x \).
So \( f'(x)=0 - 10x=- 10x \).

Answer:

If finding the derivative, \( f'(x)=-10x \)

(If the intended problem was different, e.g., evaluating at a point or finding roots, more context would be needed. But based on the function form, derivative is a likely task.)