High School

Differentiate the following function:

\[ f(x) = x^9 e^{8x} \]

A. \( f'(x) = 9x^8 e^{8x} + 72x^9 e^{8x} \)

B. \( f'(x) = 9x^9 e^{8x} + 72x^8 e^{8x} \)

C. \( f'(x) = 9x^8 e^{8x} - 72x^9 e^{8x} \)

D. \( f'(x) = 9x^9 e^{8x} - 72x^8 e^{8x} \)

Answer :

Final answer:

The function f(x) = x⁹e(8x) is differentiated using the product rule, resulting in f'(x) = 9x⁸e(8x) + 72x⁹e(8x), which is option (a).

Explanation:

To differentiate the function f(x) = x⁹e(8x), we need to apply the product rule since the function is a product of two functions: x⁹ and e(8x). According to the product rule (also known as Leibniz's law), if we have a product of two functions u(x) and v(x), then the derivative of their product u(x)v(x) is given by u'(x)v(x) + u(x)v'(x).

In this case, let u(x) = x⁹, so u'(x) = 9x⁸. And let v(x) = e(8x), so v'(x) = 8e(8x) (since the derivative of eⁿⁿ, with respect to n, is itself multiplied by the derivative of the exponent, which in this case is 8).

Applying the product rule:

f'(x) = u'(x)v(x) + u(x)v'(x)

f'(x) = 9x⁸e(8x) + x⁹(8e(8x))

f'(x) = 9x⁸e(8x) + 8x⁹e(8x)

Simplifying, we get:

f'(x) = 9x⁸e(8x) + 72x⁹e(8x)

Therefore, the correct answer is a) f'(x) = 9x⁸e(8x) + 72x⁹e(8x).