Question

solving problems with quadratic functions: tutorial
a rock is launched from a cannon. its height, h(x), can be represented by a quadratic function in terms of time, x, in seconds.
after 1 second, the rock is 205 feet in the air; after 2 seconds, it is 380 feet in the air.
the height of the can be represented by this function:
h(x) = -15x² + 220x
find the height, in feet, of the rock after 9 seconds in the air.
enter the correct answer.

Explanation:

Step1: Identify the given function

The height function is $h(x) = -15x^2 + 220x$

Step2: Substitute $x=9$ into the function

$$h(9) = -15(9)^2 + 220(9)$$

Step3: Calculate each term separately

First term: $-15(9)^2 = -15\times81 = -1215$
Second term: $220(9) = 1980$

Step4: Sum the two terms

$$h(9) = -1215 + 1980$$

Answer:

765