A firecracker shoots up from a hill 165 feet high with an initial speed of 110 feet per second. Using the formula H(t) = −16t2 + vt + s, determine how long it will take the firecracker to hit the ground.

7.2 seconds

7.5 seconds

7.8 seconds

8.1 seconds

Question

A firecracker shoots up from a hill 165 feet high with an initial speed of 110 feet per second. Using the formula H(t) = −16t2 + vt + s, determine how long it will take the firecracker to hit the ground.

7.2 seconds

7.5 seconds

7.8 seconds

8.1 seconds

anonymous · Answer

You want to find the 0's.  You can either use the quadratic formula or just plug in values

mertsj · Answer

$$0=-16t^2+110t+165$$

anonymous · Answer

considering it's multiple choice

mertsj · Answer

$$t=\frac{-110\pm \sqrt{110^{2}-4(-16)(165)}}{-32}$$

mertsj · Answer

$$t=\frac{-110\pm \sqrt{22660}}{-32}$$

sette · Answer

okay tyvm.

mertsj · Answer

$$t=\frac{-110\pm150.5}{-32}=8.14$$

mertsj · Answer

yw