The bars around the x means absolute value, which only shows that the number is positive no matter what, even if the number inside is originally negative.
The absolute value of a number is its distance from zero on the number line. Therefore, the absolute value of a number will always be positive. The distance of 5 from zero on the number line is:
H=0 Therefore: 144t-16t²=0 t (144-16t)=0 We have two equations: 1) t=0 (when the ball is released) 2) 144-16t=0 -16t=-144 t=-144 / -16=9 (this is the time )
