A snowball was thrown from a cliff. The height above ground of the snowball is modeled by the function h(t) = -16t2 + 48t + 28, where h is height in feet, and t is time in seconds. How long was the snowball in the air?
Did everything got (4t+7)(t+1)
then did 4t+7=0 i got t=-1.75 then i did the x+1=0 i got -1, its asking for how long it was in the air(seconds) what did i do wrong or how do i find the answer. help pls
see
http://www.jiskha.com/display.cgi?id=1481507804