Question

Noelle stands at the edge of a cliff and drops a rock. The height of the rock is given by the function f(x)-4.9x2 + 15, where c is the number of seconds after noelle releases her rock.

Cesar, who is standing nearby on the ground, throws a rock straight up in the air. The height of Cesar’s rock is given by the function g(x)-4.9x2+10x, where x is the number of seconds after he releases his rock.

What is the height the money the two rocks are at the same level above ground.

Answer 1

A graphing calculator shows the rocks are at the same height 1.5 seconds after they are released.

That height is 3.975 meters.

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f(x) = g(x)
-4.9x^2 +15 = -4.9x^2 +10x
15 = 10x . . . . . . . . . . . . . . . . . . add 4.9x^2
1.5 = x . . . . . . . . . . . . . . . . . . . divide by 10
f(1.5) = -4.9*2.25 +15 = 3.975