A trebuchet launches a projectile from ground level on a parabolic arc at a velocity of 40 feet per second. The equation h = −16t2 + 40t models the projectile's h height at t seconds. How long will it take for the projectile to hit its target on the ground?

Step-by-step explanation:

If the projectile is hitting something on the ground, it has a height of 0.  Sub in a 0 for the h and factor to solve for t:

Factor out a -16t to get

0 = -16t(t - 2.5) which means that either t = 0 or t = 2.5

I'd say it has to be t = 2.5, don't you?  ; )

1 x=22.52

2: 65/39=604+39x

65x-39x=604

26x=604

x=604/26

×=23.23

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this