Question

If f is a real valued function defined by f(x) = x³ + 4x + 3, then find $\rm f'(1)$ and $\rm f'(3)$.

Answer 1

Answer:

f'(1) = 7

f'(3) = 31

Step-by-step explanation:

Hi,

Given f is a real valued function and

f(x) = x³ + 4x + 3

As we know d/dx(xⁿ) = n.xⁿ⁻¹

f'(x) = 3x² + 4

f'(1) = 3.1² + 4

= 7

f'(3) = 3.3² + 4

= 31

Hope, it helps !

Answer 2

Answer:

f'(1) = 7

f'(3) =31

Step-by-step explanation:

If f is a real valued function defined by f(x) = x³ + 4x + 3,

f(x) = x³ + 4x + 3,

f'(x) = df(x)/dx   = 3x² + 4

to find f'(1)

we will put x = 1 in f'(x)

f'(1) = 3(1)² + 4

=> f'(1) = 3 + 4

=> f'(1) = 7

to find f'(3)

we will put x = 3 in f'(x)

f'(3) = 3(3)² + 4

=> f'(3) = 27 + 4

=> f'(3) =31