5.
First let's find what time the rockets are at the same height.
height of Brynn's rocket = f(x)
height of Denise's rocket = g(x)
height of Brynn's rocket = height of Denise's rocket
f(x) = g(x)
-4.9x2 + 75x = -4.9x2 + 50x + 38 Solve this equation for x . Add 4.9x2 to both sides.
75x = 50x + 38 Subtract 50x from both sides.
25x = 38 Divide both sides by 25.
x = 1.52
Now we know that after 1.52 seconds, the rockets are at the same height.
To find what this height is, plug in 1.52 for x into either function.
f(1.52) = -4.9(1.52)2 + 75(1.52) ≈ 102.7 meters