The pitch is important because of how low or high or how loud would it be. the frequency of the sound for human ear.
B. 8540, (assuming you meant 8.54 x 10 to the power 3) you move the decimal point 3 places to the right, if the decimal point can't pass any more numbers add zeros. If it confuses you to think of it this way do 10 cubed first, i.e. 10 x 10 x10 = 1000 and then do 8.54 x 1000 if thats easier for you.
The two displacement functions are
x₁ = 4t
x₂ = -161 + 48t - 4t²
where
x₁, x₂ are in meters
t is time, s
The distance between the two objects is
x = x₁ - x₂
= 4t + 161 - 48t + 4t²
x = 4t² - 44t + 161
Write this equation in the standard form for a parabola.
x = 4[t² - 11t] + 161
= 4[ (t - 5.5)² - 5.5² ] + 161
x = 4(t-5)² + 40
Ths is a parabola that faces up and has its vertex (lowest point) at (5, 40).
Therefore the closest approach of the two objects is 40 m.
The graph of x versus t confirms the result.
Answer: The distance of the closest approach is 40 m.