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?
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?
remember y represents the height from the ground, so when the rocket is on the ground then y=?
correct, so we can now substitute y=0 into the equation you were given to get:\[0=160x-5x^2=5x(32-x)\]
do you know how to solve this for x now?
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