Question

Find the derivative of f(x) = 11x2 + 5x at x = 9.

Answer 1

f(x) = 11x² + 5x

f'(x) = 22x + 5

Hence,

f'(9) = (22 * 9) + 5 = 198 + 5 = 203

Answer 2

Answer: 203

Explanation:

The given function :
`f(x) = 11x^2 + 5x`

Now, we differentiate the given function with respect to x on the both sides , we get

`f'(x) = (2)11x + 5` [Since
`(x^n)'=nx^(n-1)` ]

`\Rightarrow\ f'(x)=22x+5`

Substitute x = 9 , we get

`\Rightarrow\  f'(9)=22(9)+5\\\\\Rightarrow\ f'(9)=198+5\\\\\Rightarrow\ f'(9)=203`

Hence, the derivative of the given function at x= 9 is 203.