Question

Someone help, its calc

Answer 1

Differentiate

$\\ \rm\rightarrowtail f'(x)=\dfrac{d}{dx}(2x^2+9x)$

$\\ \rm\rightarrowtail 4x+9$

• Put x=5

f'(5):-

• 4(5)+9
• 20+9
• 29

Option C

Answer 2

instantaneous rate can be found by differentiating the function.

Here,

• f(x) = 2(x)² + 9(x)

so differentiating:

• f'(x) = d/dx (2(x)² + 9(x))

• f'(x) = 4(x) + 9

So when x = 5,

• f'(5) = 4(5) + 9

• f'(5) = 20 + 9

• f'(5) = 29