Questions: Consider the function (f(x)=5 x-x^2)
Use the limit definition to compute the following derivative values:
(f^prime(0)=)
(f^prime(1)=)
(f^prime(2)=)
(f^prime(3)=)
Transcript text: Consider the function $f(x)=5 x-x^{2}$
Use the limit definition to compute the following derivative values:
\[
\begin{array}{l}
f^{\prime}(0)= \\
f^{\prime}(1)= \\
f^{\prime}(2)= \\
f^{\prime}(3)=
\end{array}
\]
$\square$ $\square$ $\square$ $\square$
Solution
Solution Steps
To find the derivative of the function f(x)=5x−x2 at specific points using the limit definition, we use the formula for the derivative:
f′(a)=h→0limhf(a+h)−f(a)
Substitute f(x)=5x−x2 into the limit definition.
Compute the limit for each given point a.
Step 1: Define the Function and Derivative Formula
Given the function f(x)=5x−x2, we use the limit definition of the derivative:
f′(a)=h→0limhf(a+h)−f(a)
Step 2: Compute the Derivative at x=0
Substitute a=0 into the derivative formula:
f′(0)=h→0limhf(0+h)−f(0)f′(0)=h→0limh(5(0+h)−(0+h)2)−(5(0)−02)f′(0)=h→0limh5h−h2f′(0)=h→0lim(5−h)
As h→0, f′(0)=5.
Step 3: Compute the Derivative at x=1
Substitute a=1 into the derivative formula:
f′(1)=h→0limhf(1+h)−f(1)f′(1)=h→0limh(5(1+h)−(1+h)2)−(5(1)−12)f′(1)=h→0limh5+5h−1−2h−h2−4f′(1)=h→0limh4+3h−h2f′(1)=h→0lim(3−h)
As h→0, f′(1)=3.
Step 4: Compute the Derivative at x=2
Substitute a=2 into the derivative formula:
f′(2)=h→0limhf(2+h)−f(2)f′(2)=h→0limh(5(2+h)−(2+h)2)−(5(2)−22)f′(2)=h→0limh10+5h−4−4h−h2−6f′(2)=h→0limh6+h−h2f′(2)=h→0lim(1−h)
As h→0, f′(2)=1.