Question

La altura h sobre el nivel del suelo (en pies) de un cohete de juguete, t segundos después de ser lanzado, está dada por h = -16t2 + 120t. ¿Cuándo estará el cohete a 180 pies sobre el suelo?

Answer 1

The solutions are

t=2.07 sec and t=5.43 sec

Explanation:

The question in English

The height h above ground level (in feet) of a toy rocket, t seconds after it is launched, is given by h = -16t2 + 120t. When will the rocket be 180 feet above the ground?

we have

`h=-16t^(2)+120t` -----> equation A

`h=180` -----> equation B

equate the equation A and equation B

`180=-16t^(2)+120t` ------> equation C

we know that

The solution of the equation C is equal to the x-coordinate of the intersection point of the graph equation A and the graph of the equation B

so

using a graphing tool

The solutions are

t=2.07 sec and t=5.43 sec

see the attached figure to better understand the problem