20=-16(20^2) + 320(20) ?
20= -6400+6400?
20=0?
20 =/= 0
0= -16(0^2) + 320(0) ?
0=0+0?
0=0
Now, since this is geometry, t(seconds) cannot equal 0 or else the time and distance would be also 0
If i plug in 20 as t, it ends up as 20=0, which is not true.
I don't...
Homework Statement
A projectile is launched upward. Its height above the ground after t seconds is -16t^2 + 320t. After how many seconds in the air will it return to the ground? Solve algebraically.
Homework Equations
ax^2+bx+c=0 ?
-b (+/-) (Square root of b^2 -4ac)/2a ?
The...