Question

a football is kicked vertically upward from a height of 4 feet with an initial speed of 70 feet per second. the formula h = 4 + 70t - 16t^2 describes the balls height above the ground, h, in feet, t seconds after it was kicked. use this formula to find the balls height 4 seconds after it was kicked. the balls height, 4 seconds after it was kicked, was 28 feet.

Explanation:

Step1: Substitute t value

Substitute $t = 4$ into $h=4 + 70t-16t^{2}$.
$h=4 + 70\times4-16\times4^{2}$

Step2: Calculate multiplications

First calculate multiplications: $70\times4 = 280$ and $16\times4^{2}=16\times16 = 256$.
$h=4 + 280-256$

Step3: Calculate addition and subtraction

$h=(4 + 280)-256=284 - 256=28$

Answer:

28