An egg is thrown from a rooftop. The equation h = - 4.9 t 2 +

The correct answer is $18$. It's given that an egg is thrown from a rooftop and that the equation $h=-4.9t^2+9t+18$ represents this situation, where $h$ is the height of the egg above the ground, in meters, $t$ seconds after it is thrown. If follows that the height, in meters, from which the egg was thrown is the value of $h$ when $t=0$. Substituting $0$ for $t$ in the equation $h=-4.9t^2+9t+18$ yields $h\left(0\right)=-4.9{\left(0\right)}^2+9\left(0\right)+18$, or $h=18$. Therefore, according to the equation, the height, in meters, from which the egg was thrown is $18$.