The height (in metres) of a toy rocket above the ground seconds after launch is given by

MATHEMATICS · Single correct · GCSE · Mathematics · Algebra · Algebra

Problem

The height (in metres) of a toy rocket above the ground

t

seconds after launch is given by

h(t)= -4t^{2}+16t+20

. At what time does the rocket return to the ground after launch? (a)

2\text{ s}

(b)

6\text{ s}

(c)

5\text{ s}

(d)

4\text{ s}