A projectile is launched, and its height (in meters) after t seconds is modeled by . How long does it take for the projectile to reach its maximum height?
Options
A
2.8 seconds
B
3.0 seconds
C
3.5 seconds
D
4.2 seconds
Answer & Analysis
Answer
B
Analysis
The equation of height is .
To find when the projectile reaches its maximum height, complete the square.
First, factor out −4.9 from the quadratic and linear terms:
Now, complete the square for the expression inside the parentheses.
Take half of −6, square it to get 9, and add/subtract 9 inside the parentheses:
Simplify:
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