00:01
Now in this problem it is given that a ball is kicked from a height of 3 feet above the ground and the height of the ball can be modelled by the equation h of t is equals to minus 5t square plus 14t plus 3.
00:19
Now here t is the time in seconds and our task is to find that how long will it take the ball to hit the ground after it is being kicked.
00:35
So when the ball reaches the ground height will become 0, h will be equals to 0.
00:42
So i can write here that 0 will be equals to minus 5t square plus 14t plus 3.
00:53
And if you take all these terms to the left side we will get 5t square minus 14t minus 3 is equals to 0.
01:06
Now it's in quadratic equation and if you recall the standard form of the quadratic equation it is ax square plus bx plus c is equals to 0.
01:16
And from here x is equals to minus b plus minus square root b square minus 4ac divide by 2 times a.
01:28
Correct? and if you compare it we have a to be equals to 5, b is minus 14 and c is minus 3.
01:38
So use this formula to find the t from here.
01:40
T will be equals to minus b, so minus 14 plus minus square root b square.
01:48
So b square we have minus 14 square minus 4 times a is 5, c is minus 3.
01:55
Then divide by 2 times a.
02:00
A is 5...