The total time in seconds the ball will take to travel before returning the ground is 2.25 seconds.
<h3>What is factorisation?</h3>
The breaking or breakdown of an entity (such as an integer, a matrices, or a polynomials) into a products of another unit, or factors, whose multiplication results in the original number, matrix, etc., is known as factorisation or factoring in mathematics.
Calculation for the time;
Let 't' be the time in second the ball will travel.
Let H(t) be the total height travelled by the ball.
The equation of the height is given as
![H(t)=-16 t^{2}+36 t](https://tex.z-dn.net/?f=H%28t%29%3D-16%20t%5E%7B2%7D%2B36%20t)
As soon as the ball will return to the ground the total height will become zero.
So, put equation of height equal to zero.
![-16 t^{2}+36 t=0](https://tex.z-dn.net/?f=-16%20t%5E%7B2%7D%2B36%20t%3D0)
Factorise the above equation;
![-16 t\left(t-\frac{9}{4}\right)=0](https://tex.z-dn.net/?f=-16%20t%5Cleft%28t-%5Cfrac%7B9%7D%7B4%7D%5Cright%29%3D0)
Put each value equals to zero to get the value of time.
![\begin{aligned}&t=0 \mathrm{sec} \\&t=9 / 4=2.25 \mathrm{sec}\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%26t%3D0%20%5Cmathrm%7Bsec%7D%20%5C%5C%26t%3D9%20%2F%204%3D2.25%20%5Cmathrm%7Bsec%7D%5Cend%7Baligned%7D)
As, time can not be zero
Therefore, the total time taken by the ball to return to the ground is 2.25 sec.
To know more about factorisation, here
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