Answer:
12.8
Step-by-step explanation:
Given a parabola in standard form , ax² + bx + c : a ≠ 0
Then the x- coordinate of the vertex is
= -
h = 3 + 14t - 5t² ← is in standard form
with a = - 5 and b = 14, thus
= -
= 1.4
Substitute t = 1.4 into h for maximum height
h = 3 + 14(1.4) - 5(1.4)²
= 3 + 19.6 - 9.8 = 12.8