Scan QR code or get instant email to install app
The platform is reached when h = 0. It is necessary to solve the equation \(0=-t^2+3t+10\). Hence (t - 5)( t + 2) = 0. Solving the equation gives t = 5 or -2. As t is a time it is not possible for t to be -2. The rocket takes 5 seconds to reach the platform.