We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. cookie policy and privacy policy.
 
+0  
 
0
95
1
avatar

he equation y = -16t^2 + 80t describes the height (in feet) of a projectile launched from the ground at 80 feet per second. At what $t$ will the projectile reach 36 feet in height for the first time? Express your answer as a decimal rounded to the nearest tenth.

 May 21, 2019
 #1
avatar+18754 
+1

Substitute   y = 36

 

36 = -16t^2+80 t      now solve for t

16t^2-80t + 36 = 0        use quadratic formula...you will find 2 values for t....one will be the popint it is rising (the first time it reaches 36 ft) and the other will be when it is coming back down

 

Quadratic formula   a = 16     b = - 80   c = 36

\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\)

.
 May 21, 2019

10 Online Users