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 243 feet in the air; after 2 seconds, it is 452 feet in the air.
Find the height, in feet, of the rock after 5 seconds in the air.

Question

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 243 feet in the air; after 2 seconds, it is 452 feet in the air.
Find the height, in feet, of the rock after 5 seconds in the air.

anonymous · Answer

y = ax² + bx + c is the form of a quadratic equation. 
a = -16 because it's half the gravitation constant.

y = -16x² + bx + c

Start by plugging in the points (1, 243) and (2, 452) for x and y to get two equations in terms of b and c.