SOLUTION: Hello, I need help with the following math problem: "The equation {{{ y=-16t^2+26t+105 }}} describes the height (in feet) of a ball tossed up in the air at 26 feet per second

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Hello, I need help with the following math problem: "The equation {{{ y=-16t^2+26t+105 }}} describes the height (in feet) of a ball tossed up in the air at 26 feet per second      Log On


   

Question 1044085: Hello,
I need help with the following math problem:
"The equation +y=-16t%5E2%2B26t%2B105+ describes the height (in feet) of a ball tossed up in the air at 26 feet per second from a height of 105 feet above the ground. In how many seconds will the ball hit the ground? Express your answer as a decimal rounded to the nearest tenth."
Thank you,
Nicole
Found 2 solutions by advanced_Learner, ankor@dixie-net.com:
Answer by advanced_Learner(501) About Me  (Show Source):
You can put this solution on YOUR website!
solve
-16t^2+26t+105=0
using the formula
t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
t+=+%28-26+%2B-+sqrt%28+26%5E2-4%2A%28-16%29%2A105+%29%29%2F%282%2A%28-16%29%29+
gives
x+=+%28-26+%2B-+86+%29%29%2F%28-32%29+
t=3.5 or t=-1.875
time cant be negative or t=3.5 is correct answer

your feedback

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
"The equation y=-16t%5E2%2B26t%2B105 describes the height (in feet) of a ball tossed up in the air at 26 feet per second from a height of 105 feet above the ground.
In how many seconds will the ball hit the ground? Express your answer as a decimal rounded to the nearest tenth."
:
When it hits the ground y=0, therefore:
-16t%5E2%2B26t%2B105+=+0
Use the quadratic formula; a=-16; b=26; c=105
I got a positive solution: t=3.5 seconds