anonymous one year ago Medal and Fan Im not very good at algebra Arianna kicks a soccer ball off the ground and into the air with an initial velocity of 42 feet per second. Assume the starting height of the ball is 0 feet. Approximately what maximum height does the soccer ball reach? 1.3 ft 2.6 ft 26.0 ft 27.6 ft

1. anonymous

@peachpi

2. anonymous

Using the same H(t) formula from the last one H(t) = -16t² + vt + s, what's v and what's s?

3. anonymous

v is 42 s is 0?

4. anonymous

yep, so we have H(t) = -16t² + 42t so now we just need to find the vertex. For a quadratic function in the form $y=ax^2+bx+c$ the vertex is $\left( \frac{ -b }{ 2a },f \left( \frac{ -b }{ 2a } \right) \right)$ We have a = -16, b = 42, and c = 0 So for the time, find $t=\frac{ -42 }{ 2*-16 }$ Then plug it into our function to get the max height

5. anonymous

ok so it would be h(t)=-16t^2 + 42t and substitute 1.31 for t?

6. anonymous

yes

7. anonymous

and the answer becomes D correct?

8. anonymous

yes