!NO LINKS! A javelin thrower releases a javelin 6 ft from the ground with an initial vertical velocity of 18 ft/s.

Which equation can be used to find the time, t, it takes for the javelin to reach the ground?

A) –16t^2 + 18t + 6 = 0

B) –16t^2 + 18t = 0

C) –16t^2 + 6 = 0

D) –16t^2 + 6t + 18 = 0

It will be a whole number.

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.