Suppose u shoot a arrow into the air from 320 ft high building with an initial upward velocity of 128 feet/second. what is the arrows height after 3 seconds? What is the maximum height the arrow obtains before falling back down towards the ground? When does it reach its maximum height
f(t) = -16t+128+320

Question

Suppose u shoot a arrow into the air from 320 ft high building with an initial upward velocity of 128 feet/second.  what is the arrows height after 3 seconds? What is the maximum height the arrow obtains before falling back down towards the ground? When does it reach its maximum height
f(t) = -16t+128+320

misty1212 · Answer

hi!!

rachie19 · Answer

When is the arrow 100 ft above the ground?

rachie19 · Answer

Helli

misty1212 · Answer

think you copied this incorrectly right? 
$$f(t)=-16t^2+158t+320$$

misty1212 · Answer

what is the arrows height after 3 seconds? put $$f(3)=-16\times 3^2+128\times 3+320$$ to find your answer

misty1212 · Answer

What is the maximum height the arrow obtains before falling back down towards the ground?
the max is when $t=-\frac{b}{2a}=-\frac{128}{2\times (-16)}=4$ plug in $4$ to get the maximum height

misty1212 · Answer

What is the maximum height the arrow obtains before falling back down towards the ground?
set $$-16t^2+128t=320=100$$ or 
$$-16t^2+128t+220=0$$ and solve the quadratic equation for $t$

rachie19 · Answer

Ohhhhh OK I thought I did it wrong thank u so much

misty1212 · Answer

$$\color\magenta\heartsuit$$