Quadratic equation

Question

Lauren dives with her outstretched arms from a platform into the diving pool. The height of her fingertips above the pool surface can be represented by the quadratic relationship:

h=−2t^2 +4t+6

, where h is the height in metres after t seconds.

a) What is the height of her fingertips when Lauren starts the dive?

b) What is the height after: i ) 1 second:

ii ) 2 seconds:

c) How long does it take for the dive? (Hint: Use the quadratic formula to solve)

d) Explain why there is only one value for your answer to part c even though you have solved a quadratic equation that has two solutions.

Answer 1

a) h(0)=6

b) i) h(1)= 8

b) ii) h(2)= 6

c) t^2-2t-3=0

(t-3)(t+1)=0

t= 3 seconds

d) ignore t=-1 as the domain is only positive. [0.3]