13.8.33 Question Help

If an object is propelled upward from a height of s feet at an initial velocity of v feet per​ second, then its height h after t seconds is given by the equation h=−16t squared + vt +​s, where h is in feet. If the object is propelled from a height of 4 feet with an initial velocity of 64 feet per​ second, its height h is given by the equation h=−16t squared + 64t + 4.
After how many seconds is the height 6464 ​feet?

2 answers

just solve

-16t^2 + 64t + 4 = 6464
If an object is propelled upward from a height of s feet at an initial velocity of v feet per​ second, then its height h after t seconds is given by the equation h=-16t^2 + vt + s, where h is in feet. If the object is propelled from a height of 8 feet with an initial velocity lf 64 feet per second, its height h is given by the equation h=16t^2 + 64t +8. After how many seconds is the height 64 feet?