Answer:
18.25
Step-by-step explanation:
we are given a quadratic function
[tex] f(x) = - 16 {x}^{2} + 20x + 12[/tex]
where:
- f(x) represents the height
- x represents the time
To find the maximum value of f(x) in other words, the maximum height, in feet, reached by the arrow.
Differentiate both sides:
[tex] f'(x) = \dfrac{d}{dx}( - 16 {x}^{2} + 20x + 12)[/tex]
with sum differentiation rule, we acquire:
[tex] \displaystyle f'(x) = \frac{d}{dx}( - 16 {x}^{2} )+ \frac{d}{dx} 20x + \frac{d}{dx} 12[/tex]
recall that,
- differentiation of a constant is equal to 0
- [tex] \dfrac{d}{dx} {x}^{n} = n {x}^{n - 1} [/tex]
utilizing the rules we acquire:
[tex] \displaystyle f'(x) = - 32 {x}^{} + 20 [/tex]
now equate f'(x) to 0:
[tex] \displaystyle - 32 {x}^{} + 20 = 0[/tex]
solving the equation for x yields:
[tex]x _{max}= \dfrac{5}{8} [/tex]
plug in the maximum value of x into the quadratic function:
[tex]f(x )_{max}= - 16 {( \frac{5}{8} )}^{2} + 20( \frac{5}{8} ) + 12[/tex]
simplify:
[tex]f(x )_{max} = 18.25[/tex]
hence,
The maximum height reached by the arrow is 18.25 feet
