If a ball is thrown upwards from a platform 4 feet high with an initial velocity of 80 ft/sec, its height h (in feet) above the ground t seconds after it is thrown is given by the formula h = −16t 2 + 80t + 4. At what times is the ball at least 100 feet above the ground? Express your answer in interval notation

Question

If a ball is thrown upwards from a platform 4 feet high with an initial  velocity of 80 ft/sec, its height h (in feet) above the ground t seconds after  it is thrown is given by the formula h = −16t  2 + 80t + 4. At what times is  the ball at least 100 feet above the ground? Express your answer in interval  notation

mathstudent55 · Answer

Let h = 100, and solve the equation for t.

akashdeepdeb · Answer

h = −16t  2 + 80t + 4
Now as it is AT LEAsT 100
100 <= −16t  2 + 80t + 4
Solve this equatin!
That's all! :D