OpenStudy (anonymous):

a model rocket is launched from ground level into the air. its height is y, in feet, after x seconds can be represented by the equation y=160x-5x sq. what is the elapsed time in seconds, from the time the rocket is launched until it reaches ground level again?

6 years ago
OpenStudy (asnaseer):

you are given:\[y=160x-5x^2\]where y represents the height and x represents the time in seconds. when the rocket in on the ground, what do you think the value of y will be?

6 years ago
OpenStudy (asnaseer):

remember y represents the height from the ground, so when the rocket is on the ground then y=?

6 years ago
OpenStudy (anonymous):

0

6 years ago
OpenStudy (asnaseer):

correct, so we can now substitute y=0 into the equation you were given to get:\[0=160x-5x^2=5x(32-x)\]

6 years ago
OpenStudy (asnaseer):

do you know how to solve this for x now?

6 years ago
OpenStudy (anonymous):

yes thanks

6 years ago
OpenStudy (asnaseer):

yw

6 years ago