PLZ HELP...... if an object is dropped from a height of 144 feet, the function h(t)=-16t^2+144 gives the hight of the object after t seconds. when will the object hit the ground.
A.9s
B.6s
C.1.5s
D.3s

Question

anonymous · Answer

"hit the ground" means h(t)=0.
Solve $144-16t^2=0$.

anonymous · Answer

sorry the 16 is -

anonymous · Answer

So...

$16t^2=144$

What might t be? (You can ignore negative values.

anonymous · Answer

huh

anonymous · Answer

Have you ever solved a quadratic equation before?

anonymous · Answer

no

anonymous · Answer

Then reason your way through it.
You have perfect squares on each side of the equals sign, so take the square root of each side.

anonymous · Answer

square of 16 is 4 and square of 144 is 12

anonymous · Answer

Yep, so what's left?

anonymous · Answer

4 and 12

anonymous · Answer

would you divid the two numbers

anonymous · Answer

Yes, you need to get t by itself on one side of the equals sign.

anonymous · Answer

so then it would be three

anonymous · Answer

Yep. Three what? What is the question asking for?

anonymous · Answer

You can also verify the solution in the original function:

$h(t)=-16t^2+144 \space \rightarrow h(3)=-16(3)^2+144=0.$

anonymous · Answer

oh thank you very much for your help