Question

David kicks a soccer ball off the ground and in the air, with an initial velocity of 35 feet per second. Using the formula H(t) = −16t2 + vt + s, what is the maximum height the soccer ball reaches?

17.9 feet
18.2 feet
18.7 feet
19.1 feet

Answer 1

The maximum height will be the vertex

The vertex of a quadratic function is -b/2a

where the equation is ax^2 + bx + c = 0

so here we have

-16t^2 + vt + s
v is the velocity which the question says is 35

and since you're kicking the ball off the ground, the y-intercept or 's' is going to be 0

so the equation is
-16t^2 + 35t + 0 = 0

and so
'a' = -16
'b' = 35

so can you find out what -b/2a is?

that's going to be the maximum height