The equation y = -16t^2 + 60t described the height (in feet) of a projectile launched from the ground at 60 feet per second upward. In how many seconds will the projectile first reach \(30\) feet in height? Express your answer as a decimal rounded to the nearest hundredth.
+2666 The amount of time that would have passed once the ball reached 30 feet can be written by subsituting 30 in for y.
This gives: \(30 = -16t^2 + 60t\). Subtracting 30 from both sides gives us this quadratic: \(0 = -16t^2 + 60t - 30 \)
We can solve for t using the quadratic formula, which is \(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\), because the quadratic is in the form \(0 = ax^2 + bx + c\)
Can you take it from here?
