if an object is projected from a height of 640ft with an initial velocity of 96ft per second, it's height after 't' second is given by the follow equation : h=-16t^2+196t+640
after how many seconds is the height 784?
[hint: let h=784]

Question

if an object is projected from a height of 640ft with an initial velocity of 96ft per second, it's height after 't' second is given by the follow equation : h=-16t^2+196t+640
after how many seconds is the height 784? 
[hint: let h=784]

fortytherapper · Answer

Basically, you just plug in 784 for h to get

784 = -16t^2+196t+640

Let's take it one step at a time. How would you move the 640 from the right side of the equal sign to the left?

anonymous · Answer

subtract 640 from both side right? 
784=-16t^2+196t+640
-640                       -640
----------------------
144=-16t^2+196t

fortytherapper · Answer

Yes! Since the opposite of addition is subtraction.

Now for the next step, the 196t. The 196t is showing multiplication. What would you do to get that t alone?

anonymous · Answer

would you divide the 196 from the equation? 
144=-16t^2+196t
-----------------
           196