Answer:
x = -3 and 7
Step-by-step explanation:
Given the path of a diver expressed as;
h(x) = - 0.5(x^2 - 4x - 21)
The positive zero occur at when h(x) = 0
Substitue
0 = - 0.5(x^2 - 4x - 21)
-0.5x^2 + 2x + 10.5 = 0
Multiply through by -10
5x^2 - 20x - 105 = 0
x^2 - 4x - 21 = 0
x^2 - 7x+3x - 21 = 0
x(x-7)+3(x-7) = 0
(x+3)(x-7) = 0
x = -3 and 7
Hence the positive zero displacement occurs at x = -3 and 7