Jumping Cars!-Algebra 2

[helplesswithmath]

I have a math assignment for algebra 2. i dont understand it and need help. Heres the problem:
A rally car driver uses a quadratic equation to determine how far he can jump. theres a picture below to show what im doing. The equation below models the height,h, of the car to the distance,d, that the car travels on the jump.
h= -0.003621d^2 + 0.2679d

 

[soroban]

Hello, helplesswithmath!

A rally car driver uses a quadratic equation to determine how far he can jump.
The equation below models the height (h) of the car to the distance (d) that the car travels on the jump.
. . $\displaystyle h \:=\: -0.003621d^2 + 0.2679d$

When the can lands, its height is 0: .$\displaystyle h = 0$

$\displaystyle \text{We have: }\:-0.003621d^2 + 0.2679d \:=\:0 \quad\Rightarrow\quad d(0.003621d - 0.2679) \:=\:0$

$\displaystyle \text{Hence: }\;\begin{array}{cccccccccc}d \;=\; 0 \\ 0.003621d \;=\; 0 & \Rightarrow & d \;=\; \frac{0.2679}{0.003621} \;=\; 73.98508699 \end{array}$

He can jump the car about 74 feet.